Heat integration in disproportionation or transalkylation processes
Toluene disproportionation and C9/C10 transalkylation are a significant source of xylenes in a modern aromatics complex. Methods and apparatuses for improving the energy efficiency of these disproportionation and transalkylation processes are provided.
1. A process comprising the steps of:
(a) reacting, in a reactor, a reactor feed stream comprising toluene, C9 aromatics, C10 aromatics, and hydrogen over a catalyst to produce a reactor effluent stream comprising benzene and xylenes;
(b) cooling the reactor effluent stream to form a first two-phase mixture;
(c) separating the first two-phase mixture into a first liquid stream and a first vapor stream;
(d) providing at least a portion of the first liquid stream to a benzene column, wherein the portion of the first liquid stream provided to the benzene column does not contact a stabilizer column before being provided to the benzene column;
(e) recovering benzene from the first condensed liquid stream in the benzene column;
(f) cooling the first vapor stream to form a second two-phase mixture;
(g) separating the second two-phase mixture into a second liquid stream and a second vapor stream; and
(h) providing the second liquid stream to the stabilizer column.
2. The process of claim 1 , wherein the first liquid stream is substantially free of light hydrocarbons.
3. The process of claim 1 , further comprising using the reactor effluent stream to heat the reactor feed stream.
4. The process of claim 1 , further comprising using the first vapor stream to heat the reactor feed stream.
5. The process of claim 1 , wherein the reactor feed stream is heated to within about 50 degrees Celsius of the reactor effluent stream.
6. The process of claim 1 , wherein the step of cooling the reactor effluent stream to form the first two-phase mixture is performed at between about ambient temperature and the reactor temperature.
7. The process of claim 1 , wherein the step of cooling the first vapor stream to form the second two-phase mixture is performed at about ambient temperature.
8. The process of claim 1 , further comprising using the first vapor stream to heat the second condensed liquid stream.
9. The process of claim 1 , wherein the first liquid stream is not directed to a toluene column.
10. A process comprising the steps of:
(a) reacting, in a reactor, a reactor feed stream comprising toluene, C9 aromatics, C10 aromatics, and hydrogen over a catalyst to produce a reactor effluent stream comprising benzene, toluene, and xylenes;
(b) cooling the reactor effluent stream to form a first two-phase mixture;
(c) separating the first two-phase mixture into a first liquid stream and a first vapor stream;
(d) providing the first liquid stream to a stabilizer column to produce a side draw stream comprising benzene, toluene, and C8 aromatics;
(e) providing the side draw stream to an extractive distillation unit;
(f) cooling the first vapor stream to form a second two-phase mixture; and
(g) separating the second two-phase mixture into a second liquid stream and a second vapor stream.
11. The process of claim 10 , further comprising providing the second liquid stream to the stabilizer column.
12. The process of claim 10 , wherein the first liquid stream is substantially free of light hydrocarbons.
13. The process of claim 10 , further comprising using the reactor effluent stream to heat the reactor feed stream.
14. The process of claim 10 , further comprising using the first vapor stream to heat the reactor feed stream.
15. The process of claim 10 , wherein the reactor feed stream is heated to within about 50 degrees Celsius of the reactor effluent stream.
16. The process of claim 10 , wherein the step of cooling the reactor effluent stream to form the first two-phase mixture is performed at between about ambient temperature and the reactor temperature.
17. The process of claim 10 , wherein the step of cooling the first vapor stream to form the second two-phase mixture is performed at about ambient temperature.
18. The process of claim 10 , further comprising using the first vapor stream to heat the second liquid stream.