# US 9,943,775 B2 · Flexible process for treating solvent, such as monoethylene glycol, used in natural gas extraction

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- Number: US 9,943,775 B2
- Document ID: US9943775B2
- Status: Granted
- Kind: B2
- Application number: 14/547,233
- Filed: 2014-11-19
- Published: 2015-05-28
- Granted: 2018-04-17
- Earliest claimed: 2013-11-22
- Assignees: Prosernat
- Applicants: Prosernat
- Inventors: Jeremie Esquier; Bernard Chambon; Christian Streicher
- Web page: https://patentgrep.com/patent/US9943775B2

## CPC

- B01D 3/06: Flash distillation
- B01D 3/10: Vacuum distillation (B01D3/12 takes precedence)
- B01D 3/148: {in combination with at least one evaporator}
- B01D 3/34: with one or more auxiliary substances
- B01D 53/1425: {Regeneration of liquid absorbents}
- C07C 29/80: by distillation
- B01D 2252/2023: Glycols, diols or their derivatives
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

The invention concerns a flexible process for purifying a solvent which inhibits the formation of hydrates during gas processing, in particular monoethylene glycol (MEG), said solvent having a boiling point which is higher than that of water and, at least at one point in time, being mixed with water and salts, the process operating in a different manner with the same facility as a function of the quantity of salts in the MEG to be treated. The process operates in accordance with a phase known as reclaiming (separation of salts under vacuum followed by vacuum distillation) when the salts content exceeds the precipitation threshold and if not, the process operates in a regeneration phase (absence of separation of salts and no operation under vacuum). Advantageously, the change is made under the control of means for testing the salts.

## Claims

### Claim 1

A process for purifying a hydrate formation inhibiting solvent, said solvent having a boiling point which is higher than that of water and, at least at one point in time, being mixed with water and salts, the process comprising:
optionally, a pre-treatment of said solvent to be treated, said pre-treatment separating at least a portion of the hydrocarbons, condensates, and gases, and said pre-treatment optionally comprising adding a chemical neutralization agent;
determining whether the quantity of salts in a treated mixture is above, equal to, or below a precipitation threshold;
a reclaiming phase carried out when the quantity of salts in said solvent, which has optionally been pre-treated, is equal to or greater than the precipitation threshold in the treated mixture;
said phase comprising a vacuum flash, operating at a pressure which is below atmospheric pressure and at a temperature which is below the degradation temperature of the solvent, by which a stream of solvent containing salts and a vaporized stream of solvent and water are obtained, said stream of solvent and water being vacuum distilled at a pressure which is substantially equal to that prevailing in said vacuum flash in order to separate the water and recover a stream of purified solvent, the salts being separated from said stream of solvent containing the salts, then the solvent obtained being recycled to the flash;
wherein when said quantity of salts in the treated mixture is below a precipitation threshold, stopping the reclaiming phase and carrying out a phase termed regeneration;
said regeneration phase comprising releasing the vacuum, the solvent to be treated, which has optionally been pre-treated, undergoing a flash step, operating at a pressure greater than or equal to atmospheric pressure and at a temperature which is below the degradation temperature of the solvent, by which a first stream of purified solvent and a stream of solvent and water are obtained, said stream of solvent and water being distilled under a pressure substantially equal to that prevailing in said flash, the water being separated and a second stream of purified solvent being obtained, said second stream being mixed with said first stream and/or recycled to said flash.

### Claim 2 (depends on 1)

The process according to claim 1, in which the solvent is monoethylene glycol.

### Claim 3 (depends on 1)

The process according to claim 1, in which the solvent is an alkanolamine.

### Claim 4 (depends on 3)

The process according to claim 3, in which the solvent is selected from the group formed by monoethanolamine (MEA), diethanolamine (DEA) and methyldiethanolamine (MDEA).

### Claim 5 (depends on 1)

The process according to claim 1, in which the solvent to be treated does not undergo a treatment for separating divalent salts.

### Claim 6 (depends on 1)

The process of claim 1, wherein the pressure of the vacuum flash is in the range of 0.2 to 0.5 bar absolute.

### Claim 7 (depends on 1)

The process of claim 1, wherein the pressure of the regeneration phase is in the range 1 to 2 bar absolute.

### Claim 8

A process for purifying a hydrate formation inhibiting solvent, said solvent having a boiling point which is higher than that of water and, at least at one point in time, being mixed with water and salts, the process comprising:
optionally, a pre-treatment of said solvent to be treated, said pre-treatment separating at least a portion of the hydrocarbons, condensates, and gases, and said pre-treatment optionally comprising adding a chemical neutralization agent;
a reclaiming phase carried out when the quantity of salts in said solvent, which has optionally been pre-treated, reaches a precipitation threshold in the treated mixture;
said phase comprising a vacuum flash, operating at a pressure which is below atmospheric pressure and at a temperature which is below the degradation temperature of the solvent, by which a stream of solvent containing salts and a vaporized stream of solvent and water are obtained, said stream of solvent and water being vacuum distilled at a pressure which is substantially equal to that prevailing in said vacuum flash in order to separate the water and recover a stream of purified solvent, the salts being separated from said stream of solvent containing the salts, then the solvent obtained being recycled to the flash;
wherein when said quantity of salts in the treated mixture is below a precipitation threshold, stopping the reclaiming phase and carrying out a phase termed regeneration;
said regeneration phase comprising releasing the vacuum, the solvent to be treated, which has optionally been pre-treated, undergoing a flash step, operating at a pressure greater than or equal to atmospheric pressure and at a temperature which is below the degradation temperature of the solvent, by which a first stream of purified solvent and a stream of solvent and water are obtained, said stream of solvent and water being distilled under a pressure substantially equal to that prevailing in said flash, the water being separated and a second stream of purified solvent being obtained, said second stream being mixed with said first stream and/or recycled to said flash, and
wherein said process includes at least one regeneration phase and at least one reclaiming phase.