Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
AN IN-SITU PROCESS FOR CLEANING A GAS PROCESSING PLANT
Document Type and Number:
WIPO Patent Application WO/2020/197376
Kind Code:
A1
Abstract:
The present invention relates to an in-situ process for cleaning gas processing plant equipment during processing, the process comprising the steps of providing a homogenous suspension comprising a dessicant and a substance to dehydrate a feed gas stream; separating the suspension from the dehydrated gas; removing carbonaceous deposits and/or oily residue present in the suspension; and treating the suspension in order to substantially degrade the substance and separate the dessicant therefrom.

Inventors:
LOO WEE CHEN (MY)
CHAN YOK PENG (MY)
Application Number:
PCT/MY2019/050057
Publication Date:
October 01, 2020
Filing Date:
September 17, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SEECHEM HORIZON SDN BHD (MY)
International Classes:
B01D53/28; B01D53/74; C10G75/00
Domestic Patent References:
WO2019036166A12019-02-21
Foreign References:
US6425942B12002-07-30
US5882486A1999-03-16
US20170233320A12017-08-17
US20150361018A12015-12-17
US20170183587A12017-06-29
US20180030360A12018-02-01
US20190062187A12019-02-28
US20080051472A12008-02-28
Attorney, Agent or Firm:
LOK, Choon Hong (MY)
Download PDF:
Claims:
CLAIMS

1. An in-situ process for cleaning gas processing plant equipment during processing, the process comprising the steps of

providing a homogenous suspension comprising a dessicant and a substance to dehydrate a feed gas stream;

separating the suspension from the dehydrated gas;

removing carbonaceous deposits and/or oily residue present in the suspension; and

treating the suspension in order to substantially degrade the substance and separate the dessicant therefrom.

2. An in-situ process according to claim 1, wherein the substance is a nanoemulsion.

3. An in-situ process according to claim 1 or claim 2, wherein the dessicant is glycol.

4. An in-situ process according to any one of claims 1 to 3, wherein the step of separating the suspension from the dehydrating gas is achieved by flashing the mixture thereof to a low pressure level in a flash vessel.

5. An in-situ process according to any one of claims 1 to 4, wherein the step of removing the carbonaceous deposit and/or oily residue from the suspension is achieved by filtration.

6. An in-situ process according to any one of claims 1 to 5, wherein the step of treating the suspension is accomplished by heating the suspension at a temperature of 120-200 °C.

7. An in- situ process according to any one of claims 1 to 6, wherein the amount of the substance present is less than 2% by weight, with respect to the total weight of the homogenous suspension.

8. An in- situ process according to any one of claims 1 to 7 further comprising a step of recirculating the separated glycol to provide glycol supply for mixing with the substance.

9. An in-situ process according to claim 2, wherein the nanoemulsion comprises an aqueous phase in 0.5 to 40% by weight of total composition; a non-aqueous phase in 15 to 90% by weight of total composition; a surfactant in 2 to 60% by weight of total composition; and a compound having Chemical structure I in 1 to 30% by weight of total composition,

in which R1, R2, R3 and R4 are linear, branched or aromatic carbon-containing substituents having 2 to 26 carbon atoms and n is an integer ranges from 1 to 100, wherein each of the substituents comprises an alkyl group, carbonyl group, a carboxylic group, an amine group, or an amide group.

10. An in-situ process according to claim 9, wherein the nanoemulsion further comprising a co-surfactant in a proportion of 1-30% (w/v), the co-surfactant is selected from short-chain surfactant, short-chain non-ionic surfactant, alcohol, amide and mixture thereof.

11. An in-situ process according to claim 9 or 10, wherein the nanoemulsion is an oil-in-water nanoemulsion, wherein the aqueous phase is between about 0.5- 40% by weight of the nanoemulsion.

12. An in-situ process according to any one of claims 1 to 11 further comprising a step of further mixing the homogenous suspension with a corrosion inhibitor selected from phosphate ester, amine salt of polycarboxylic acid, quaternary ammonium salt, quaternary iminium salt, amidoamine, imidazoline, ethoxylated fatty amine, ethoxylated fatty diamine and mixtures thereof

13. An in-situ process according to any one of claims 1 to 12 further comprising a step of further mixing the homogenous suspension with a defoamer selected from an alcohol having a carbon chain length of 6-30, surfactant, carboxylic salt having a carbon chain length of 6-30, copolymer of ethylene oxide and propylene oxide, saturated hydrocarbon, fatty acid having a carbon chain length of 6-30, silicone or polyfunctional silicone oil, fluorocarbon and a mixture thereof.

Description:
AN IN-SITU PROCESS FOR CLEANING A GAS PROCESSING PLANT

FIELD OF INVENTION The present invention relates to an in- situ process for cleaning a gas processing plant. Particularly, the present invention relates to an in-situ process for removing carbonaceous deposit and oily residue from the gas processing plant equipment during processing, thereby eliminating the need of dismantling equipments and shutting down the processing operation.

BACKGROUND OF THE INVENTION

In deepwater gas production facilities, moisture tends to accumulate in the feed gas, thereby increasing the risk of hydrate formation that potentially causes blockage of pipeline. Removal of hydrates in the deepwater gas transport system is generally difficult to achieve and the remediation work can be costly. To prevent the hydrate formation, glycol is used as a desiccant for removing moisture in the feed gas to inhibit the formation of hydrates. During the glycol dehydration process, lean glycol is injected or sprayed through a nozzle and introduced into a gas contactor. The lean glycol is then contacted with the feed gas in the gas contactor to absorb moisture therefrom. While the rich glycol absorbs high content of moisture, the glycol also mixes with hydrocarbon residues, in which the hydrocarbon residues will later form carbonaceous deposit in spaces along the gas processing system. The spaces along the gas processing system may include but not limited to a gas well, a vessel, and an equipment connected to the gas well or the vessel. As a result, the carbonaceous deposit formation may render the gas processing system to be dysfunctional due to ineffective in heat transfer and blockage at the spraying nozzles in the gas processing facilities. In order to remove blockages and deposits, the gas processing system is required to be shut down for several days or weeks to conduct maintenance or cleaning process. In present, the equipment clogged with the carbonaceous deposit has to be dismantled and delivered to warehouse for cleaning. Alternatively, a new equipment is installed to replace the equipment clogged with the carbonaceous deposit. Such approaches do not only obstruct the gas production operation but also incurs high cost to solve the blockage problem. Therefore, there is a need for developing an alternative cleaning process for removing carbonaceous deposit and/or oily residue from the gas processing plant that can overcome the problem aforementioned.

SUMMARY OF INVENTION

The main aspect of the present invention is to provide a cleaning process for removing carbonaceous deposit and oily residue from gas processing plant equipment, in which the cleaning process can be conducted in-situ without the need of dismantling equipment and shutting down the processing operation.

Another aspect of the present invention is to provide an in-situ process for cleaning the gas processing plant equipment that is cost-saving and environmental friendly, in which the process employs a nanoemulsion that is readily biodegradable, non- corrosive and non-toxic for removal of the carbonaceous deposit and oily residue.

At least one of the preceding objects is met, in whole or in part, by the present invention, in which one of the embodiments of the present invention is an in-situ process for cleaning gas processing plant equipment during processing, the process comprising the steps of providing a homogenous suspension comprising a dessicant and a substance to dehydrate a feed gas stream; separating the suspension from the dehydrated gas; removing carbonaceous deposits and/or oily residue present in the suspension; and treating the suspension in order to substantially degrade the substance and separate the dessicant therefrom.

In accordance with a preferred embodiment, the substance is preferably a nanoemulsion. Preferably, the nanoemulsion comprises an aqueous phase in 0.5 to 40% by weight of total composition; a non-aqueous phase in 15 to 90% by weight of total composition; a surfactant in 2 to 60% by weight of total composition; and a compound having Chemical structure I in 1 to 30% by weight of total composition,

in which R 1 , R 2 , R 3 and R 4 are linear, branched or aromatic carbon-containing substituents having 2 to 26 carbon atoms and n is an integer ranges from 1 to 100, wherein each of the substituents comprises an alkyl group, carbonyl group, a carboxylic group, an amine group, or an amide group.

It is preferable that the nanoemulsion further comprising a co-surfactant in a proportion of 1-30% (w/v), the co-surfactant is selected from short-chain surfactant, short-chain non-ionic surfactant, alcohol, amide and mixture thereof

Advantageously, the nanoemulsion is an oil-in-water nanoemulsion. More advantageously, the aqueous phase present is between about 0.5-40% by weight of the nanoemulsion.

Preferably, the dessicant used in the present invention is glycol. Preferably, the step of separating the suspension from the dehydrating gas is achieved by flashing the mixture thereof to a low pressure level in a flash vessel.

Advantageously, the step of removing the carbonaceous deposit and/or oily residue from the suspension is achieved by filtration. Conveniently, the step of treating the suspension is accomplished by heating the suspension at a temperature of 120-200 °C. According to a preferred embodiment, the amount of the substance present is less than 2% by weight, with respect to the total weight of the homogenous suspension.

In another preferred embodiment, the process aforementioned further comprising a step of recirculating the separated dessicant to provide dessicant supply for mixing with the substance.

Preferably, the process aforementioned further comprising a step of further mixing the homogenous suspension with a corrosion inhibitor selected from phosphate ester, amine salt of polycarboxylic acid, quaternary ammonium salt, quaternary iminium salt, amidoamine, imidazoline, ethoxy lated fatty amine, ethoxy lated fatty diamine and mixtures thereof.

Advantageously, the process aforementioned further comprising a step of further mixing the homogenous suspension with a defoamer selected from an alcohol having a carbon chain length of 6-30, surfactant, carboxylic salt having a carbon chain length of 6-30, copolymer of ethylene oxide and propylene oxide, saturated hydrocarbon, fatty acid having a carbon chain length of 6-30, silicone or polyfunctional silicone oil, fluorocarbon and a mixture thereof In one embodiment, the surfactant preferably contains both hydrophobic groups and hydrophilic groups. Non-ionic surfactant may also be used in the present invention as the defoamer. On the other hand, the exemplary saturated hydrocarbon used in the present invention includes but not limited to mineral oil, polyether or its derivatives with hydroxyl functional group.

The present preferred embodiment of the invention consists of novel features and a combination of parts hereinafter fully described and illustrated in the accompanying drawings and particularly pointed out in the appended claims; it being understood that various changes in the details may be effected by those skilled in the arts but without departing from the scope of the invention or sacrificing any of the advantages of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the invention shall be described according to the preferred embodiments of the present invention and by referring to the accompanying description and drawings. However, it is to be understood that limiting the description to the preferred embodiments of the invention and to the drawings is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications without departing from the scope of the appended claim.

The present invention relates to an in-situ process for cleaning gas processing plant equipment during processing, the process comprising the steps of providing a homogenous suspension comprising a dessicant and a substance to dehydrate a feed gas stream; separating the suspension from the dehydrated gas; removing carbonaceous deposits and/or oily residue present in the suspension; and treating the suspension in order to substantially degrade the substance and separate the dessicant therefrom.

It is preferable that the dessicant used in the present invention is glycol. On the other hand, the substance is preferably a nanoemulsion.

More particularly, one of the preferred embodiment of the present invention discloses an in-situ process for cleaning a gas processing plant equipment during processing, the process comprising the steps of mixing a nanoemulsion with glycol to form a homogenous suspension; contacting the suspension with a feed gas stream in a dehydration zone to provide dehydrated gas; flashing the mixture to a low pressure level in a flash vessel to separate the dehydrated gas from the suspension; filtering the suspension through a filtration means to remove carbonaceous deposit and/or oily residue which has been absorbed by the suspension; and subjecting the suspension to heating in order to separate the glycol from the nanoemulsion, such that the nanoemulsion is being degraded during the step of heating.

According to the preferred embodiment, the cleaning process is carried out in-situ at the gas processing plant. In one embodiment, the gas processing plant equipment comprises a dehydration zone, a heat exchanger zone, a gas contactor, a gas flashing zone, a means for spraying or injecting glycol, and a gas storage vessel. As the process of the present invention enables in-situ cleaning of the gas processing plant equipment during processing, user does not need to dismantle the equipment aforementioned for cleaning purpose to remove carbonaceous deposit and oily residue therefrom. While performing the in-situ cleaning process, the gas processing operation remains uninterrupted.

Preferably, a blockage in the spraying nozzle in the gas processing plant is detected using a pressure gauge. Typically, a higher pressure detected in the gas processing plant indicates a possible blockage therein. When a higher pressure level is detected, the gas processing system may be prompted to initiate the in-situ cleaning process of the present invention. Alternatively, when a blockage is suspected, user can manually initiate the in-situ process of the present invention to commence cleaning of the gas processing plant equipment.

In accordance with the preferred embodiment, the nanoemulsion is mixed with lean glycol in a vessel to form a homogenous suspension. In another embodiment, the nanoemulsion may be injected into a flowline that carries the lean glycol in order to be mixed therewith. The amount of nanoemulsion used is preferably less than 2% by weight, with respect to the total weight of the homogenous suspension. In one embodiment, the glycol employed in the present invention is selected from triethylene glycol (TEG), di ethylene glycol (DEG), ethylene glycol (MEG), and tetraethylene glycol (TREG).

The nanoemulsion comprises an aqueous phase in 0.5 to 40% by weight of total composition; a non-aqueous phase in 15 to 90% by weight of total composition; a surfactant in 2 to 60% by weight of total composition; and a compound having Chemical structure I in 1 to 30% by weight of total composition,

in which R 1 , R 2 , R 3 and R 4 are linear, branched or aromatic carbon-containing substituents having 2 to 26 carbon atoms and n is an integer ranges from 1 to 100, wherein each of the substituents comprises an alkyl group, carbonyl group, a carboxylic group, an amine group, or an amide group.

Preferably, the nanoemulsion further comprising a co-surfactant in a proportion of 1- 30% (w/v). More preferably, the co-surfactant is selected from short-chain surfactant, short-chain non-ionic surfactant, alcohol, amide and mixture thereof.

Advantageously, the nanoemulsion is an oil-in-water nanoemulsion. More advantageously, the aqueous phase present is between about 0.5-40% by weight of the nanoemulsion. The nanoemulsion as set forth in the description above is biodegradable, non-corrosive and non-toxic.

It is preferable that homogenous suspension is further mixed with an additive selected from corrosion inhibitor, pH buffer, defoamer and a mixture thereof during the removal of the carbonaceous deposit and oily residue from the gas processing plant equipment. Pursuant to a preferred embodiment, the corrosion inhibitor is selected from phosphate ester, amine salt of polycarboxylic acid, quaternary ammonium salt, quaternary iminium salt, amidoamine, imidazoline, ethoxylated fatty amine, ethoxylated fatty diamine and mixtures thereof

It is preferable that the defoamer is selected from an alcohol having a carbon chain length of 6-30, surfactant, carboxylic salt having a carbon chain length of 6-30, copolymer of ethylene oxide and propylene oxide, saturated hydrocarbon, fatty acid having a carbon chain length of 6-30, silicone or polyfunctional silicone oil, fluorocarbon and a mixture thereof. In a preferred embodiment, the surfactant preferably contains both hydrophobic groups and hydrophilic groups. Non-ionic surfactant may also be used in the present invention as the defoamer. On the other hand, the exemplary saturated hydrocarbon used in the present invention includes but not limited to mineral oil, polyether or its derivatives with hydroxyl functional group.

After the homogenous suspension is prepared, the suspension is preferably introduced into a dehydration zone, wherein the zone is provided with a continuous stream of feed gas, particularly the natural gas. When the feed gas is contacted with the homogenous suspension, the moisture in the feed gas is absorbed by the lean glycol in the suspension. On the other hand, the oily residue that has been absorbed by the glycol during its contact with the gas, will be suspended in the nanoemulsion.

As the homogenous suspension is carried along the gas processing plant equipments by the continuous feed gas stream, the homogenous suspension will come into contact with the carbonaceous deposit that may have been deposited on the surface of the equipment or pipeline of the gas processing plant. When in contact, the carbonaceous deposit will be suspended in the nanoemulsion. To separate the homogenous suspension from the feed gas, the mixture is flashed to a lower pressure level in order to form a first fraction enriched with the feed gas and a second fraction enriched with the homogenous suspension. Thereafter, the fraction enriched with the homogenous suspension is preferably subjected to filtration through a filtration medium. In an embodiment, the filtration medium may be a filter membrane, filter cloth, filter composite or a filter mesh. The carbonaceous deposit and the oily residue will be collected on the filtration medium.

The filtered homogenous suspension comprising rich glycol and nanoemulsion is then preferably subjected to a heating process. During the heating process, the nanoemulsion is preferably degraded at a high temperature while the moisture is evaporated and released from the glycol to produce lean glycol. In a preferred embodiment, the heating process is conducted at a temperature of about 120-200 °C. More preferably, the filtered homogenous suspension is heated at a temperature of about 170-180 °C when the glycol used is TEG.

The lean glycol obtained from the heating process is preferably recirculated in the gas processing system to provide glycol supply for mixing with the nanoemulsion in the next cycle of the in-situ cleaning process.

Although the invention has been described and illustrated in detail, it is to be understood that the same is by the way of illustration and example, and is not to be taken by way of limitation. The scope of the present invention is to be limited only by the terms of the appended claims.