Method and apparatus for continuous production of mesophase pitch
A process and apparatus for the continuous conversion of isotropic carbonaceous materials into anisotropic mesophase pitch is disclosed. The invention disclosed herein addresses the need for lower production costs compared with traditional batch mesophase conversion of isotropic pitch. A unique thermal processing and in-process separation of reacted mesophase from the continuous matrix of fresh or partially reacted isotropic pitch is provided. Potential uses are for further continuous processing into carbon fibers or carbon form densification.
1. An apparatus for continuous production of mesophase pitch comprising:
a generally cylindrical reactor vessel having an outer vessel wall, a top end and a bottom end, said vessel having an upper temperature zone and a lower temperature zone;
a reactor head mounted on said top end of said vessel;
a cylindrical tube baffle centered and mounted along a central axis of said vessel and spaced inwardly from said outer vessel wall forming (i) an inside space within said cylindrical tube baffle, (ii) an outside space between said cylindrical tube baffle and said outer vessel wall and (iii) a circulation path through said inside space and said outside space;
an inlet for feeding isotropic pitch into the upper temperature zone;
an agitator for circulating fluid along said circulation path in said vessel through said inside space and said outside space;
a mesophase separator located between said upper temperature zone and said lower temperature zone;
a first heating element for heating said upper temperature zone;
a second heating element for heating said lower temperature zone; and
an outlet for providing mesophase pitch for further processing.
2. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said agitator is powered by a motor.
3. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said agitator further comprises at least one axial flow impeller at an end of said inside space and at least one high-shear impeller within said inside space.
4. An apparatus for continuous production of mesophase pitch according to claim 1 further comprising at least one sparge ring to dispense an inert gas in a direction of fluid flow within said outside space.
5. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said inlet further comprises a branch line to feed isotropic pitch to a second reactor vessel in parallel to said vessel.
6. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said reactor head is flanged.
7. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said bottom end of said outer vessel wall further comprises a conical bottom in which said lower temperature zone is located.
8. An apparatus for continuous production of mesophase pitch according to claim 7 wherein said conical bottom is flanged.
9. An apparatus for continuous production of mesophase pitch according to claim 8 wherein higher density mesophase material accumulates in said conical bottom of said vessel.
10. An apparatus for continuous production of mesophase pitch according to claim 7 wherein said outlet is located in said conical bottom of said vessel.
11. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said first and second heating elements are selected from the group consisting of radiant heaters, contact resistance heaters, induction heaters and molten salt or metal when an external jacket is employed.
12. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said first heating element is configured to maintain said upper temperature zone at a temperature necessary to maintain reaction conditions.
13. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said second heating element is configured to maintain said lower temperature zone at a temperature below that necessary to maintain reaction conditions but above that necessary to maintain mesophase pitch in a liquid state.
14. An apparatus for continuous production of mesophase pitch according to claim 1 further comprising one or more additional temperature zones to control reaction conditions more precisely.
15. An apparatus for continuous production of mesophase pitch according to claim 1 further comprising a transfer pump to extract mesophase pitch from said outlet.
16. An apparatus for continuous production of mesophase pitch according to claim 1 wherein mesophase pitch exits said outlet by reactor operating pressure.
17. An apparatus for continuous production of mesophase pitch according to claim 4 wherein at least one of said sparge ring and said agitator continuously circulates fluid including unreacted isotropic pitch from said lower temperature zone back to said upper temperature zone for further reaction.
18. An apparatus for continuous production of mesophase pitch according to claim 1 wherein said inlet is located near said top end of said outer vessel wall.