Method for removing a foulant from a gas stream with minimal external refrigeration
AssigneeHall Labs LLC
InventorsLarry Baxter, Eric Mansfield, Christopher Hoeger
Life of this patent
Estimating the term…
Abstract
A process for removing a foulant from a gas stream. The gas stream is cooled in a series of heat exchangers, causing a portion of the foulant to desublimate and become entrained in a cryogenic liquid. This foulant slurry stream is pressurized, cooled, and separated into a pressurized foulant solid stream and the cryogenic liquid stream. The pressurized foulant solid stream is melted to produce a liquid foulant stream. Heat exchange processes, both internal and external, are provided that close the heat balance of the process. In this manner, the foulant is removed from the gas stream.
Claims20
A process for removing a foulant from a gas stream, the process comprising:
- cooling the gas stream having the foulant in a first heat exchanger to a first temperature that is above a frosting point of the foulant to form a cooled gas stream;
- cooling the cooled gas stream in a second heat exchanger against a cryogenic liquid stream to a second temperature that is below the frosting point of the foulant, wherein a portion of the foulant within the cooled gas stream de-sublimates, thereby forming a foulant depleted gas stream and a solid foulant stream, the solid foulant stream becoming entrained in the cryogenic liquid stream, forming a foulant slurry stream;
- withdrawing the foulant slurry stream from the second heat exchanger;
- withdrawing the foulant depleted gas stream from the second heat exchanger;
- pressurizing the foulant slurry stream and cooling the foulant slurry stream across a third heat exchanger to produce a pressurized foulant slurry stream that is at or exceeds the triple point of the foulant;
- separating the pressurized foulant slurry stream into a pressurized foulant solid stream and the cryogenic liquid stream;
- melting the pressurized foulant solid stream in a melting heat exchanger to produce a liquid foulant stream;
- heating the liquid foulant stream in the first heat exchanger to form a warmed foulant fluid stream;
- providing the warmed foulant fluid stream to a side inlet of a distillation column, wherein the distillation column separates the warmed foulant fluid stream into a cooled liquid overhead foulant stream and a warmed cryogenic liquid stream;
- providing the cooled liquid overhead foulant stream to the melting heat exchanger to warm the pressurized solid foulant stream, causing the cooled liquid overhead foulant stream to cool into an overhead foulant stream, wherein a portion of the overhead foulant stream is recycled to a top inlet of the distillation column, while the remainder of the overhead foulant stream is removed;
- providing a portion of the warmed cryogenic liquid stream to a recycle warming heat exchanger, while the balance of the warmed cryogenic liquid stream is cooled across the first heat exchanger to become a cooled cryogenic liquid recycle stream, wherein the recycle warming heat exchanger warms the portion of the cooled cryogenic liquid stream before returning the portion of the warmed cryogenic liquid stream to a bottom inlet of the distillation column;
- providing a first portion of external refrigeration to the first heat exchanger and the third heat exchanger using a first reverse Rankine refrigeration cycle having a first refrigerant, wherein the first reverse Rankine refrigeration cycle comprises the steps of:
- a. compressing the first refrigerant;
- b. condensing the first refrigerant;
- c. expanding the first refrigerant;
- d. vaporizing the first refrigerant;
- wherein step (b) occurs in the first heat exchanger, at a third temperature near the foulant triple point such that the first refrigerant condenses,
- wherein step (d) occurs in the third heat exchanger;
- whereby the foulant is removed from the gas stream.
Dependencies are inferred from the claim text.