CA1233941A - Particle form evaporation start-up - Google Patents
Particle form evaporation start-upInfo
- Publication number
- CA1233941A CA1233941A CA000429620A CA429620A CA1233941A CA 1233941 A CA1233941 A CA 1233941A CA 000429620 A CA000429620 A CA 000429620A CA 429620 A CA429620 A CA 429620A CA 1233941 A CA1233941 A CA 1233941A
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- vessel
- seed
- recited
- bed
- temperature
- Prior art date
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Abstract
Abstract of the Disclosure A seed is supplied to a particle form evaporator to form a seed bed. The rate at which seed is supplied is controlled in response to the temperature of the seed bed. The seed bed can be used to facilitate start-up of the particle form evaporator.
Description
~3~
PARTICLE FORM ~APORATIO~ STA~T-UP
My invention relates -to particle form evaporation. In one aspect my invention re'lates to the start-up of par-ticle form evaporators.
:fn another aspect my invention relates -to a seed system for par-ticle Eorm evaporators.
BACKGROUND
Particle form evaporation is described in U.S. pstents 4,31Q,973 and 4,2~3,091. The reader is encouraged to consult and s-tudy these sources of information to facilitate a comprehensive and thorough understanding of my present inven-tion.
In brief summary particle form evaporation involves the evaporation of solvent or liquid from a po]ymer. This is accomplished by introducing a polymer-containing solution or a mixture of polymer and liquid into an agitated bed of hot polymer particles. The hot agitated bed, typically contained in a cylindrical vessel, facilitates evaporation of solvent or liquid. The introduced polymer upon agitation and drying assumes a particle form and replaces other dry polymer particles in the bed which are removed as the product of the process.
Agitation is typically accomplished by positioning within the vessel containing the polymer particle bed a mechanical agita-tion means such as, for examp:Le, rotating mixer blades. The term 'blade is intended to 'be 'broadly construed and includes, for example, paddles, rods, pins, etc. Ag:itation of the 'bed causes an input of energy into the system wh:ich heats the polymer particles. or good results the bed should be 3~
hea-ted to a temperature of a-t least abou-t the boiling point of the solvent or liquid. The heat can be supplied by agitation alone or in combination with other sources of heat such as, for example, a hot gas directed through the bed or a heating jacket posi-tioned around the bed.
The feed (polymer solution or polymer-liquid mixture) can be introduced :into the bed in any of many ways. For example the feed can be sprayed into the becl if -the feed is sufficiently fluid. A less fluid feed such as, for example, one premixed with filler can be extruded into the bed. Many o-ther methods of feed introduction are within the scope of this invention and the capability of those of ordinary skill in the ar-t.
Particle form evapora-tion is not limited to any particular polymer and the scope of this invention should be interpreted accordingly.
We note, however, that the process is especially well suited for the recovery of dry rubbery polymer such as, for example, styrene-butadiene copolymer from a rubbery polymer solution (as produced in a solution polymerization process) or from a rubbery polymer-con-taining latex (as produced in an emulsion polymerization process).
A problem encountered in the practice of the particle form evaporation process is that of start-up. Without a bed of hot agitated particles ready to receive the feed the feed builds up in -the system without adequate evaporation of solvent or liquid.
S = ary of the Invention In accordance with my invention a seed is supplied to a particle form evaporator to build up an agitated bed of hot particles before introduction of polymer solution or polymer-liquid mixture into the bed. The seed is comprised of solid particles. The rate at which seed is supplied to the particle form evaporator can be regulated in response to the temperature of the bed.
Objects of the Invention 3 It is an object of my invention to provide an improved particle form evaporation process and system.
It is another object of my invention to improve the efficiency oE particle form evaporation start-up.
These objects and other objects and advantages of my invention will be apparent upon a study of this disclosure and the appended claims.
3~l Brief Description of the Drawing Figure l depicts a start-up system for a par-ticle form evaporator.
Detailed Description of the Invention Because it is not practical to start introduction of feed (i.e.
polymer solution or polymer-liquid mixture) until a bed of hot particles is established in the particle Norm evaporator I have invented a process and apparatus for establishing a start-up bed. In accordance with my invention a seed comprising solid particles is passed to the particle form evaporator to build up a bed of hot seed particles in the vessel.
The solid seed particles can be of any solid ma-terial. It is yreferred, however -that the seed be comprised of the same type of polymer that is to be introduced into the particle form evaporator as part of the feed. This is preferred because it reduces the complexity of the process and the possibility of contamination. 0-ther materials that can be used as seed include, by way of nonlimiting example, polymers not similar in type to the polymer in the feed, sand, fillers, poly-ethylene pellets, etc. The seed particles can be formed by grinding, pelleting or otherwise processing the material to obtain small units.
The seed, once in the bed, provides resistance to the agitation means. This resistance generates heat within the bed. or best opera-tion of the particle form evaporator the seed particle bed must be heated up to a temperature of at least about the boiling point ox -the solvent or liquid to be evaporated. vower temperatures can be used but this will necessitate longer residence times in the particle form evaporator. To protect the product it is generally desired to maintain the temperature of the bed below about that point at which significan-t thermal degradation of the polymer will occur.
In addition to the heat generated by mechanical agitation of the seed particle bed, heat can optionally be supplied to the bed by passi.ng a hot gas into the bed, by positioning a heating jacket around the bed-containing vessel or otherwise supplying an additional source of heat to the bed.
~3~
The seed can be fed into the particle form evaporator from a .source such as, for example, a hopper or other container. For efficien-t operation after an initial bed has been built up the rate a-t which seed is fed into the particle form evaporator is controlled in response -to the temperature of the bed. The control system illustrated in Figure l and explained below is an example oE how -this procedure can be imple-mented. A rate should be es-tablished such that the temperature of the bed is at least high enough to e-ffect evaporation of solvent or liquid when introduced with the Eeed. It is preEerred, for good evapora-tion, that the temperacure of the bed be at leas-t about the boiling point of the solvent or liquid. The rate at which seed is fed into the particle form evaporator should also be suf-ficiently high such that the tempera ture of the bed does no-t reach a point at which substantial thermal degrada-tion oE the polymer occurs.
In an embodiment of this invention the formation of the seed bed (i.e. the bed of solid par-ticles) in the particle form evapora-tor is begun by introducing into the particle form evaporator seed at a rale independent of temperature. After the bed has been sufficiently built up, such thaw the bed temperature can be sensed by the means chosen for that purpose, the rate of seed introduction is controlled in response to that temperature.
Figure l depi.cts one embodimen-t of my invention. The particle form evaporator l is a cylindrical Bessel, the axis of rotation of which is horizontally aligned. positioned within the vessel is a mechanical agitation means comprised of an axially aligned shaft 2 and blades 3 attached thereto. The shaft 2 is rota-ted by a motor (not shown).
Ro-tation of the shaft 2 drives the blades 3 and causes agitation of -the particle bed (when present).
A secondary uni-t is positioned below the particle form evapo-rator l to receive polymer particles that fall through the opening createclby gate 5. The secondary unit is a cylindr:ical vessel, the axis of rotat:ion of which is vertially aligned. N2 (or some other inert gas) is passed through the unit 4. Polymer which falls into the secondary unit forms a second bed which is agitated by a second agitation means. This 3S second agitation means is comprised of a shaft 6 and blacles 7 attached ~3~
thereto. The shaft 6 is rota-ted by a motor (not shown) Ro-tation of the shaft 6 drives the blades 7 and causes agitation of the second'bed.
Evaporated solvent or liquid is removed :Erom the system through conduit 8 or at 9. The dried polymer product is removed through the opening created by gate lO.
Before operation begins both the particle form evaporator 1 and the secondary unit 4 are empty of -Eeed and particles. It is clesired to build up a bed of hot particles in the particle form evapora-tor 1 'be-Eore the feed is irltroduced through introduction means 11 into the particle form evaporator 1.
Seed is supplied to and s-tored in a hopper 12. The seed can be particles of any material. It can be, for example, sand or polymer.
For the purposes of this illus-tration the seed is comprised of dry, ground or pelleted, styrene-bu-tadiene copolymer.
The mechanical agitators in the particle form evaporator 1 and in the secondary uni-t 4 are running even though the vessels are emp-ty.
The entire system is filled with an inert gas such as N2 to displace air. Switch 13 is activated to start blower 14 and to open valves 15 and 16. This establishes a flow of N2 (introduced through the Eilter 17) through the conduit used to feed seed into the particle form evaporator 1.
Having established this N2 flow a ro-tary valve motor switch lo is activated to turn on a motor l9 which drives a rotary valve 20. The rotary valve 20 and the blower 14 are interlocked so that the rotary valve won'-t -turn unless the blower is on. A minimum speed regulator 21 controls the motor l9 such that the rotary valve 20 is rotated at a min:imum speed to begin ieeding seed lnto the conduit 25. The seed is blown through valve 15 into the particle form evaporator l where build-up of the particle 'bed begins. Note that because oE the rotating `blades the seed bed Eorms against the wall of the vessel. The bed provides resistance to the rotation of the blades which in turn causes the input o:E heat into the bed.
~3~
After a bed has been at least partially built wi-thin the particle form evaporator 1 control switches -Erom 21 to a feed con-troller 2~. The feed controller 22 in normal opera-tion (i.e. after start-up) is used to regulate the inpu-t of feed through introduction means 11 but during start-up is used to regulate the amoun-t of seed Eed into the particle form evaporator 1. The temperature within the particle bed is sensed by a temperature sensing means such as, Eor example, a thermocouple) positioned in the particle form evaporator 1. The temperature is used by a temperature con-troller 23 to regulate the feed controller 22. In this manner the rate at which seed is fed into the particle Eorm evapora-tor is regulated in response to the temperature of the bed.
Valve 5 is ac-tuated in response to the load on the motor (not shown) that drives the rotation of shaft 2. On start-up with the motor unloaded (i.e. no particle bed) valve 5 is closed. If the rate at which seed is fed into the bed is too high then the seed will no-t have time to heat up to the desired temperature before -the motor is loaded ànd seed is dumped through opened valve 5. recall that the temperature of the bed should be at least about the boiling point of the solvent or liquid in the feed to be introduced through 11 after start-up. If -the rate at which seed is fed into the bed is too low then the load on the motor will be built up slowly, the residence time of the particles in the bed will be too long (because valve 5 will not open un-til the load has built Up) and the bed will overheat. The bed overheats if it reaches a temperature sufficiently high to cause significan-t thermal degradation of the polymer in the feed to be introduced through 11 after s-tart-up.
accordingly, the seed is fed into the particle form evaporator at a rate such tha-t the bed temperature is main-tained within the desired range (i.e.
at least about -the boiling point of -the solvent or liquid but not above the therma:L degradation point o:E the polymer).
Seed discharged from -the secondary unit 4 can be recycled to the hopper 10.
Once the bed is built up and the desired temperature is established in the particle form evaporator 1 and a second particle bed in the secondary unit 4 is built up (suEficient to cover the polymer outlet opening at gate 10) the system is ready to receive the feed. At this point switch 13 is -turned off and feed switch 24 is turned on.
~33~
Valves 15 and 16 close automatically so that vapors will not en-ter the seed system. The feed, regulated by feed controller 22, is then in-~ro-duced through 11 into the par-ticle form evaporator 1. The rate at which feed is introduced can be controlled in response -to the temperature of the particle bed.
Assuming that the polymer in -the feed is a styrene-butadiene copolymer of the type used as seed then polymer can be immediately removed as product through gate lO. If the seed is a material other tharl the polymer in the feed and it is no-t desired to have such seed material combined with the dried polymer produc-t then provision must be made to first separately collect the outpu-t through gate 10 until the seed is no longer present in the output.
PARTICLE FORM ~APORATIO~ STA~T-UP
My invention relates -to particle form evaporation. In one aspect my invention re'lates to the start-up of par-ticle form evaporators.
:fn another aspect my invention relates -to a seed system for par-ticle Eorm evaporators.
BACKGROUND
Particle form evaporation is described in U.S. pstents 4,31Q,973 and 4,2~3,091. The reader is encouraged to consult and s-tudy these sources of information to facilitate a comprehensive and thorough understanding of my present inven-tion.
In brief summary particle form evaporation involves the evaporation of solvent or liquid from a po]ymer. This is accomplished by introducing a polymer-containing solution or a mixture of polymer and liquid into an agitated bed of hot polymer particles. The hot agitated bed, typically contained in a cylindrical vessel, facilitates evaporation of solvent or liquid. The introduced polymer upon agitation and drying assumes a particle form and replaces other dry polymer particles in the bed which are removed as the product of the process.
Agitation is typically accomplished by positioning within the vessel containing the polymer particle bed a mechanical agita-tion means such as, for examp:Le, rotating mixer blades. The term 'blade is intended to 'be 'broadly construed and includes, for example, paddles, rods, pins, etc. Ag:itation of the 'bed causes an input of energy into the system wh:ich heats the polymer particles. or good results the bed should be 3~
hea-ted to a temperature of a-t least abou-t the boiling point of the solvent or liquid. The heat can be supplied by agitation alone or in combination with other sources of heat such as, for example, a hot gas directed through the bed or a heating jacket posi-tioned around the bed.
The feed (polymer solution or polymer-liquid mixture) can be introduced :into the bed in any of many ways. For example the feed can be sprayed into the becl if -the feed is sufficiently fluid. A less fluid feed such as, for example, one premixed with filler can be extruded into the bed. Many o-ther methods of feed introduction are within the scope of this invention and the capability of those of ordinary skill in the ar-t.
Particle form evapora-tion is not limited to any particular polymer and the scope of this invention should be interpreted accordingly.
We note, however, that the process is especially well suited for the recovery of dry rubbery polymer such as, for example, styrene-butadiene copolymer from a rubbery polymer solution (as produced in a solution polymerization process) or from a rubbery polymer-con-taining latex (as produced in an emulsion polymerization process).
A problem encountered in the practice of the particle form evaporation process is that of start-up. Without a bed of hot agitated particles ready to receive the feed the feed builds up in -the system without adequate evaporation of solvent or liquid.
S = ary of the Invention In accordance with my invention a seed is supplied to a particle form evaporator to build up an agitated bed of hot particles before introduction of polymer solution or polymer-liquid mixture into the bed. The seed is comprised of solid particles. The rate at which seed is supplied to the particle form evaporator can be regulated in response to the temperature of the bed.
Objects of the Invention 3 It is an object of my invention to provide an improved particle form evaporation process and system.
It is another object of my invention to improve the efficiency oE particle form evaporation start-up.
These objects and other objects and advantages of my invention will be apparent upon a study of this disclosure and the appended claims.
3~l Brief Description of the Drawing Figure l depicts a start-up system for a par-ticle form evaporator.
Detailed Description of the Invention Because it is not practical to start introduction of feed (i.e.
polymer solution or polymer-liquid mixture) until a bed of hot particles is established in the particle Norm evaporator I have invented a process and apparatus for establishing a start-up bed. In accordance with my invention a seed comprising solid particles is passed to the particle form evaporator to build up a bed of hot seed particles in the vessel.
The solid seed particles can be of any solid ma-terial. It is yreferred, however -that the seed be comprised of the same type of polymer that is to be introduced into the particle form evaporator as part of the feed. This is preferred because it reduces the complexity of the process and the possibility of contamination. 0-ther materials that can be used as seed include, by way of nonlimiting example, polymers not similar in type to the polymer in the feed, sand, fillers, poly-ethylene pellets, etc. The seed particles can be formed by grinding, pelleting or otherwise processing the material to obtain small units.
The seed, once in the bed, provides resistance to the agitation means. This resistance generates heat within the bed. or best opera-tion of the particle form evaporator the seed particle bed must be heated up to a temperature of at least about the boiling point ox -the solvent or liquid to be evaporated. vower temperatures can be used but this will necessitate longer residence times in the particle form evaporator. To protect the product it is generally desired to maintain the temperature of the bed below about that point at which significan-t thermal degradation of the polymer will occur.
In addition to the heat generated by mechanical agitation of the seed particle bed, heat can optionally be supplied to the bed by passi.ng a hot gas into the bed, by positioning a heating jacket around the bed-containing vessel or otherwise supplying an additional source of heat to the bed.
~3~
The seed can be fed into the particle form evaporator from a .source such as, for example, a hopper or other container. For efficien-t operation after an initial bed has been built up the rate a-t which seed is fed into the particle form evaporator is controlled in response -to the temperature of the bed. The control system illustrated in Figure l and explained below is an example oE how -this procedure can be imple-mented. A rate should be es-tablished such that the temperature of the bed is at least high enough to e-ffect evaporation of solvent or liquid when introduced with the Eeed. It is preEerred, for good evapora-tion, that the temperacure of the bed be at leas-t about the boiling point of the solvent or liquid. The rate at which seed is fed into the particle form evaporator should also be suf-ficiently high such that the tempera ture of the bed does no-t reach a point at which substantial thermal degrada-tion oE the polymer occurs.
In an embodiment of this invention the formation of the seed bed (i.e. the bed of solid par-ticles) in the particle form evapora-tor is begun by introducing into the particle form evaporator seed at a rale independent of temperature. After the bed has been sufficiently built up, such thaw the bed temperature can be sensed by the means chosen for that purpose, the rate of seed introduction is controlled in response to that temperature.
Figure l depi.cts one embodimen-t of my invention. The particle form evaporator l is a cylindrical Bessel, the axis of rotation of which is horizontally aligned. positioned within the vessel is a mechanical agitation means comprised of an axially aligned shaft 2 and blades 3 attached thereto. The shaft 2 is rota-ted by a motor (not shown).
Ro-tation of the shaft 2 drives the blades 3 and causes agitation of -the particle bed (when present).
A secondary uni-t is positioned below the particle form evapo-rator l to receive polymer particles that fall through the opening createclby gate 5. The secondary unit is a cylindr:ical vessel, the axis of rotat:ion of which is vertially aligned. N2 (or some other inert gas) is passed through the unit 4. Polymer which falls into the secondary unit forms a second bed which is agitated by a second agitation means. This 3S second agitation means is comprised of a shaft 6 and blacles 7 attached ~3~
thereto. The shaft 6 is rota-ted by a motor (not shown) Ro-tation of the shaft 6 drives the blades 7 and causes agitation of the second'bed.
Evaporated solvent or liquid is removed :Erom the system through conduit 8 or at 9. The dried polymer product is removed through the opening created by gate lO.
Before operation begins both the particle form evaporator 1 and the secondary unit 4 are empty of -Eeed and particles. It is clesired to build up a bed of hot particles in the particle form evapora-tor 1 'be-Eore the feed is irltroduced through introduction means 11 into the particle form evaporator 1.
Seed is supplied to and s-tored in a hopper 12. The seed can be particles of any material. It can be, for example, sand or polymer.
For the purposes of this illus-tration the seed is comprised of dry, ground or pelleted, styrene-bu-tadiene copolymer.
The mechanical agitators in the particle form evaporator 1 and in the secondary uni-t 4 are running even though the vessels are emp-ty.
The entire system is filled with an inert gas such as N2 to displace air. Switch 13 is activated to start blower 14 and to open valves 15 and 16. This establishes a flow of N2 (introduced through the Eilter 17) through the conduit used to feed seed into the particle form evaporator 1.
Having established this N2 flow a ro-tary valve motor switch lo is activated to turn on a motor l9 which drives a rotary valve 20. The rotary valve 20 and the blower 14 are interlocked so that the rotary valve won'-t -turn unless the blower is on. A minimum speed regulator 21 controls the motor l9 such that the rotary valve 20 is rotated at a min:imum speed to begin ieeding seed lnto the conduit 25. The seed is blown through valve 15 into the particle form evaporator l where build-up of the particle 'bed begins. Note that because oE the rotating `blades the seed bed Eorms against the wall of the vessel. The bed provides resistance to the rotation of the blades which in turn causes the input o:E heat into the bed.
~3~
After a bed has been at least partially built wi-thin the particle form evaporator 1 control switches -Erom 21 to a feed con-troller 2~. The feed controller 22 in normal opera-tion (i.e. after start-up) is used to regulate the inpu-t of feed through introduction means 11 but during start-up is used to regulate the amoun-t of seed Eed into the particle form evaporator 1. The temperature within the particle bed is sensed by a temperature sensing means such as, Eor example, a thermocouple) positioned in the particle form evaporator 1. The temperature is used by a temperature con-troller 23 to regulate the feed controller 22. In this manner the rate at which seed is fed into the particle Eorm evapora-tor is regulated in response to the temperature of the bed.
Valve 5 is ac-tuated in response to the load on the motor (not shown) that drives the rotation of shaft 2. On start-up with the motor unloaded (i.e. no particle bed) valve 5 is closed. If the rate at which seed is fed into the bed is too high then the seed will no-t have time to heat up to the desired temperature before -the motor is loaded ànd seed is dumped through opened valve 5. recall that the temperature of the bed should be at least about the boiling point of the solvent or liquid in the feed to be introduced through 11 after start-up. If -the rate at which seed is fed into the bed is too low then the load on the motor will be built up slowly, the residence time of the particles in the bed will be too long (because valve 5 will not open un-til the load has built Up) and the bed will overheat. The bed overheats if it reaches a temperature sufficiently high to cause significan-t thermal degradation of the polymer in the feed to be introduced through 11 after s-tart-up.
accordingly, the seed is fed into the particle form evaporator at a rate such tha-t the bed temperature is main-tained within the desired range (i.e.
at least about -the boiling point of -the solvent or liquid but not above the therma:L degradation point o:E the polymer).
Seed discharged from -the secondary unit 4 can be recycled to the hopper 10.
Once the bed is built up and the desired temperature is established in the particle form evaporator 1 and a second particle bed in the secondary unit 4 is built up (suEficient to cover the polymer outlet opening at gate 10) the system is ready to receive the feed. At this point switch 13 is -turned off and feed switch 24 is turned on.
~33~
Valves 15 and 16 close automatically so that vapors will not en-ter the seed system. The feed, regulated by feed controller 22, is then in-~ro-duced through 11 into the par-ticle form evaporator 1. The rate at which feed is introduced can be controlled in response -to the temperature of the particle bed.
Assuming that the polymer in -the feed is a styrene-butadiene copolymer of the type used as seed then polymer can be immediately removed as product through gate lO. If the seed is a material other tharl the polymer in the feed and it is no-t desired to have such seed material combined with the dried polymer produc-t then provision must be made to first separately collect the outpu-t through gate 10 until the seed is no longer present in the output.
Claims (29)
1. A particle form evaporation start-up process comprising:
(i) introducing seed into a vessel to form a seed bed within said vessel, (ii) mechanically agitating said seed bed, and (iii) controlling the rate at which seed is introduced into said vessel in response to the temperature of said agitated seed bed;
wherein said seed comprises solid particles.
(i) introducing seed into a vessel to form a seed bed within said vessel, (ii) mechanically agitating said seed bed, and (iii) controlling the rate at which seed is introduced into said vessel in response to the temperature of said agitated seed bed;
wherein said seed comprises solid particles.
2. A process as recited in claim 1 wherein said seed bed is agitated by rotating blades.
3. A process as recited in claim 1 wherein the temperature of said seed bed is sensed with a temperature sensing means in said vessel and wherein said temperature is used to control the introduction of seed into said vessel.
4. A process as recited in claim 1 wherein said seed is introduced into said vessel by blowing said seed through a conduit leading to said vessel.
5. A process as recited in claim 1 wherein said seed is comprised of polymer.
6. A process as recited in claim 1 further comprising (iv) introducing a feed into said vessel after said seed bed has been established; wherein said feed comprises a member selected from the group consisting of (a) a solution comprising polymer and solvent and (b) a mixture comprising polymer and liquid.
7. A process as recited in claim 6 wherein said feed is introduced into said vessel after a suitable temperature has been established in said seed bed; wherein said suitable temperature is at least about the temperature necessary to effect evaporation in said vessel of a substantial portion of said solvent or said liquid.
8. A process as recited in claim 6 wherein said feed is introduced into said vessel after a suitable temperature has been established in said seed bed; and wherein said suitable temperature is at least about the boiling point in said vessel of said solvent or of said liquid.
9. A process as recited in claim 8 wherein said suitable temperature is further defined to be less than about the temperature at which substantial thermal degradation of said polymer in said feed occurs.
10. A process as recited in claim 6 wherein said seed is comprised of the same type of polymer as the polymer in said feed.
11. An apparatus comprising:
(i) a vessel having positioned therein a rotatable shaft with at least one blade attached to said shaft, (ii) a container for containing solid particles, (iii) a conduit in open communication with said vessel, (iv) a means for introducing solid particles from said container into said conduit, (v) a means for forcing solid particles through said conduit and into said vessel, (vi) a temperature sensing means in said vessel, and (vii) a means for controlling in response to said temperature the rate at which solid particles are introduced into said vessel.
(i) a vessel having positioned therein a rotatable shaft with at least one blade attached to said shaft, (ii) a container for containing solid particles, (iii) a conduit in open communication with said vessel, (iv) a means for introducing solid particles from said container into said conduit, (v) a means for forcing solid particles through said conduit and into said vessel, (vi) a temperature sensing means in said vessel, and (vii) a means for controlling in response to said temperature the rate at which solid particles are introduced into said vessel.
12. An apparatus as recited in claim 11 wherein said means for forcing solid particles through said conduit and into said vessel is a blower.
13. An apparatus as recited in claim 11 wherein said temperature sensing means is a thermocouple.
14. A method employing the apparatus of claim 11 comprising:
(a) causing said rotatable shaft to rotate about its axis of rotation, (b) introducing solid particles from said container into said conduit, and (c) introducing said solid particles into said vessel through said conduit to form a bed of solid particles in said vessel.
(a) causing said rotatable shaft to rotate about its axis of rotation, (b) introducing solid particles from said container into said conduit, and (c) introducing said solid particles into said vessel through said conduit to form a bed of solid particles in said vessel.
15. A method as recited in claim 14 wherein said solid particles are blown through said conduit and into said vessel.
16. A method as recited in claim 14 wherein said solid particles are introduced into said vessel after said rotatable shaft has begun to rotate.
17. A method as recited in claim 14 wherein said conduit and said vessel are filled with an inert gas before solid particles are introduced into said vessel.
18. A method as recited in claim 14 further comprising:
(d) sensing the temperature in said bed of solid particles with a temperature sensing means, and (e) controlling in response to said temperature the rate at which solid particles are introduced into said vessel.
(d) sensing the temperature in said bed of solid particles with a temperature sensing means, and (e) controlling in response to said temperature the rate at which solid particles are introduced into said vessel.
19. A method as recited in claim 18 further comprising:
(f) introducing into said vessel a feed comprising a member selected from a solution comprising polymer and solvent and a mixture comprising polymer and liquid.
(f) introducing into said vessel a feed comprising a member selected from a solution comprising polymer and solvent and a mixture comprising polymer and liquid.
20. A method as recited in claim 19 wherein said rate is controlled in such a manner that a suitable temperature is established in said bed; and wherein said suitable temperature is at least about the temperature necessary to effect evaporation in said vessel of a substantial portion of said solvent or liquid.
21. A method as recited in claim 19 wherein said rate is controlled in such a manner that a suitable temperature is established in said bed; and wherein said suitable temperature is at least about the boiling point in said vessel of said solvent or of said liquid.
22. A method as recited in claim 21 wherein said suitable temperature is further defined to be less than about the temperature at which significant thermal degradation of said polymer will occur.
23. A method as recited in claim 18 wherein the formation of said bed of solid particles is begun by introducing solid particles into said vessel at a rate independent of temperature until said bed is sufficiently built up such that said temperature sensing means can sense the temperature of said bed; and wherein after said bed is sufficiently built up said method proceeds in accordance with (d) and (e).
24. A method as recited in claim 23 wherein a minimum speed regulator is used to facilitate introduction of solid particles into said vessel at a rate independent of temperature.
25. A method as recited in claim 14, 16 or 18 wherein said solid particles are comprised of polymer.
26. A method as recited in claim 19, 20 or 23 wherein said solid particles are comprised of polymer of the same type as the polymer in said feed.
27. A process comprising building a seed bed in a particle form evaporator by (i) introducing seed into said particle form evaporator to form said seed bed, (ii) mechanically agitating said seed bed, and (iii) controlling the rate at which seed is introduced into said particle form evaporator in response to the temperature of said seed bed; and wherein said seed comprises solid particles.
28. A process as recited in claim 27 wherein feed is introduced into said particle form evaporator after said seed bed has been established; and wherein said feed is selected from a solution comprising polymer and solvent and a mixture comprising polymer and liquid.
29. A process as recited in claim 28 wherein said feed is not introduced into said particle form evaporator until a suitable temperature has been established in said seed bed; and wherein said suitable temperature is at least about the boiling point in said particle form evaporator of said solvent or liquid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42722182A | 1982-09-29 | 1982-09-29 | |
| US427,221 | 1982-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1233941A true CA1233941A (en) | 1988-03-08 |
Family
ID=23693962
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000429620A Expired CA1233941A (en) | 1982-09-29 | 1983-06-03 | Particle form evaporation start-up |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1233941A (en) |
-
1983
- 1983-06-03 CA CA000429620A patent/CA1233941A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20050308 |