Closed-loop thermal servicing of solvent-refining columns
A method of thermally servicing a solvent-refining column comprises: running a closed-loop water-steam system past a top and bottom of a first column, the first column containing at least a solvent and impurities; boiling pressurized water in the closed-loop water-steam system to steam using first heat from the top of the first column; compressing the steam in the closed-loop water-steam system to a higher temperature; and providing second heat to the first column by condensing the steam at the bottom of the first column after compression.
1. A system that thermally services a solvent-refining column, the system comprising:
a column wherein impurities are removed from a solvent, the column having a top and a bottom;
a first heat exchanger;
a second heat exchanger;
a compressor;
an expansion valve;
a closed-loop water-steam system having water-steam therein and connecting the first heat exchanger, the second heat exchanger, the compressor, and the expansion valve wherein:
the compressor is arranged between the first heat exchanger and the second heat exchanger;
the expansion value is arranged between the second heat exchanger and the first heat exchanger;
the first heat exchanger transfers heat to the water-steam from the top of the column;
the compressor increases a temperature of the water-steam received from the first heat exchanger;
the second heat exchanger transfers heat from the water-steam to the bottom of the column; and
the expansion valve reduces the temperature of the water-steam.
2. The system of claim 1 , further comprising another column including the solvent, the impurities and water wherein the water is separated from the solvent and the impurities and a third heat exchanger arranged between the compressor and the second heat exchanger, wherein the third heat exchanger transfers heat from the water-steam to the bottom of the another column.
3. The system of claim 1 , further comprising a first bypass in the closed-loop water-steam system for selectively bypassing, at least partially, the first heat exchanger.
4. The system of claim 1 , further comprising a heater positioned between the compressor and the second heat exchanger wherein the heater heats the water-steam.
5. The system of claim 1 , further comprising a second bypass in the closed-loop water-steam system wherein the second bypass selectively bypasses, at least partially, the second heat exchanger.
6. The system of claim 2 , further comprising a heater positioned between the compressor and the third heat exchanger wherein the heater heats the water-steam.
7. The system of claim 1 , wherein the impurities have a boiling point that is less than about 2% lower or higher than a boiling point of the solvent.
8. The system of claim 7 , wherein the solvent is n-methyl pyrrolidone and wherein the impurities are partial oxides of the n-methyl pyrrolidone.
9. The system of claim 2 , further comprising a third bypass in the closed-loop water-steam system wherein the third bypass selectively bypasses, at least partially, the third heat exchanger.