(19)
(11)EP 3 704 480 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
03.03.2021 Bulletin 2021/09

(21)Application number: 17724107.2

(22)Date of filing:  04.04.2017
(51)Int. Cl.: 
G01N 33/28  (2006.01)
C09K 8/54  (2006.01)
(86)International application number:
PCT/IB2017/000497
(87)International publication number:
WO 2018/185510 (11.10.2018 Gazette  2018/41)

(54)

SCREENING METHOD FOR ASSESSING THE H2S RELEASE CAPACITY OF A SULFUR CONTAINING SAMPLE

SCREENING-VERFAHREN ZUR BEURTEILUNG DER H2S-FREISETZUNGSKAPAZITÄT EINER SCHWEFELHALTIGEN PROBE

PROCÉDÉ DE CRIBLAGE PERMETTANT D'ÉVALUER LA CAPACITÉ DE LIBÉRATION DE H2S D'UN ÉCHANTILLON CONTENANT DU SOUFRE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
09.09.2020 Bulletin 2020/37

(73)Proprietor: TOTAL SE
92400 Courbevoie (FR)

(72)Inventors:
  • LORIAU, Matthieu
    64140 Lons (FR)
  • MAYOU, David
    64230 Lescar (FR)

(74)Representative: Plasseraud IP 
66, rue de la Chaussée d'Antin
75440 Paris Cedex 09
75440 Paris Cedex 09 (FR)


(56)References cited: : 
DE-A1- 19 741 809
US-A- 5 922 087
JP-A- 2011 169 802
US-A1- 2016 090 655
  
  • HWANG Y ET AL: "Identification and quantification of sulfur and nitrogen containing odorous compounds in wastewater", WATER RESEARCH, ELSEVIER, AMSTERDAM, NL, vol. 29, no. 2, February 1995 (1995-02), pages 711-718, XP004035483, ISSN: 0043-1354, DOI: 10.1016/0043-1354(94)00145-W
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

Field of the invention



[0001] The invention relates to an analytical method and a screening method.

[0002] The invention relates in particular to a method for assessing the H2S release capacity of a liquid sample containing one or more sulfur compounds which are able to be degraded into gaseous H2S with temperature. Such method can be used in order to screen various liquid compositions, such as additives for the oil industry, and select the one which has the lowest H2S release capacity.

Background



[0003] The oil and gas industry employs corrosion inhibitor additives in order to protect oil and gas production installations against internal corrosion. These additives are commonly formulated as liquid blends of various chemical compounds, including sulfur compounds such as thiols or thioethers. When stocked in a tank, the sulfur compounds contained in these additives can be thermally degraded, thereby leading to the production of H2S. H2S is known to be harmful to human and even deadly at concentration as low as 500 ppm. Because it is heavier than air, the H2S released from the vent of an additive containing stock tank will accumulate on ground thereby creating a deadly atmosphere for people working in such an environment.

[0004] Portable H2S detectors are available that are able to detect the presence of H2S in the atmosphere. The detector can be a paper comprising lead acetate that becomes black in contact with H2S (formation of lead sulfur). The detector also can be an electrochemical detector able to detect a H2S above a certain threshold value. However, these detectors are not able to measure the level of H2S in the atmosphere. Therefore, they cannot be used to determine which additives release the highest amounts of H2S.

[0005] Hwang et al. Wat. Res. Vol. 29, No. 2, pp. 711-718 discloses a method for determining the amount of dissolved sulfur containing compounds at every step in an existing wastewater treatment process.

[0006] Experiments consisting of ageing an additive in a closed flask and analyzing the degradation product can be conducted in order to evaluate the quantity of H2S released from the additive over time (static headspace concentration). An example of this kind of experiment is disclosed in US 2016/0090655. However, these experiments do not correctly simulate the real conditions of a stock tank having a vent. Indeed, in a closed flask, the degradation of the sulfur compounds occurs until equilibrium is reached. In a stock tank, the equilibrium can be never reached because H2S is evacuated through the vent. Therefore, the amount of H2S formed in a closed flask is lower than the one formed in a stock tank, and thus is not representative of real conditions. Moreover, such experiments are not easy to handle because they require different steps such as taking a sample of the degradation product and analyzing the sample into a gas chromatography. These steps must be performed by a well-trained operator under safety conditions in order to avoid the contamination of the degradation product or because the handled products are dangerous. Furthermore, these experiments are time consuming.

[0007] Consequently, there is a need for a method for assessing the amount of H2S released from a sample under conditions which can simulate the conditions in a stock tank and which does not require de-formulation of said sample (i.e. build up the formulation of the sample).

[0008] There is also a need for a method for screening various liquid samples and select the one which has the lowest H2S release capacity.

[0009] The invention meets this need by providing a method which is fast, easy to carry out and safe.

Summary of the invention



[0010] A first object of the present invention is a method for assessing the H2S release capacity of a liquid sample containing one or more sulfur compounds which are able to be degraded into gaseous H2S with temperature, said method comprising the following steps:
  1. a) Placing a volume of the liquid sample in a purge vessel so as to obtain a liquid phase and a gaseous phase in a flask;
  2. b) Purging the gaseous phase with an inert gas stream for a determined period of time;
  3. c) Passing the purged gaseous phase through a H2S trap;
  4. d) Recovering H2S from the H2S trap;
  5. e) Measuring the recovered H2S,
wherein the purge vessel (3) is kept at a temperature from 40°C to 60°C,
wherein the liquid sample is a corrosion inhibitor, an oil wetting agent, a solid dispersing agent, a scale inhibitor, an anti-foulant, an oxygen scavenger, a foaming agent, or a mixture thereof.

[0011] In one embodiment, the liquid sample has a boiling temperature of at least 80°C.

[0012] In one embodiment, the purge vessel is kept at a temperature from 45°C to 55°C.

[0013] In one embodiment, the period of time of the purging step b) is from 2 min to 12 min, in particular from 3 min to 10 min, more particularly from 5 min to 8 min.

[0014] In one embodiment, the trapping step c) is performed by cryofocusing, adsorption, gas-solid reaction with a captation mass, in particular by cryofocusing on a polymeric non-polar adsorbent with liquid nitrogen.

[0015] In one embodiment, the measuring step d) is performed by gas chromatography possibly coupled with mass spectrometry, thermogravimetric analysis possibly coupled with mass spectrometry, elemental analysis for sulfur, in particular by gas chromatography coupled with mass spectrometry.

[0016] A second object of the invention is a method for selecting a liquid sample among a group of different liquid samples, said method comprising the following steps:
  • Assessing the H2S release capacity of each liquid sample according to the method previously described;
  • Selecting the sample which has the lowest H2S release capacity.


[0017] A third object of the invention is a method for selecting a liquid sample, said method comprising the following steps:
  • Assessing the H2S release capacity of each liquid sample according to the method previously described;
  • Comparing the H2S release capacity with a threshold value.

Brief description of the figures



[0018] Figure 1 is schematic representation of an apparatus for carrying out the method of the invention. Figure 2 is a graph illustrating the H2S release capacity expressed as chromatographic pic area of thioglycol acid as a function of the volume of thioglycol acid, said H2S release capacity being determined according to the method of the invention.

Detailed description of the invention



[0019] A first aspect of the invention is a method for assessing the H2S release capacity of a liquid sample containing one or more sulfur compounds which are able to be degraded into gaseous H2S with temperature, said method comprising the following steps:
  1. a) Placing a volume of the liquid sample in a purge vessel so as to obtain a liquid phase and a gaseous phase in a flask;
  2. b) Purging the gaseous phase with an inert gas stream for a determined period of time;
  3. c) Passing the purged gaseous phase through a H2S trap;
  4. d) Recovering H2S from the H2S trap;
  5. e) Measuring the recovered H2S.


[0020] The method of the invention can be applied to any liquid composition comprising one or more sulfur compounds which are able to be degraded into gaseous H2S with temperature, i.e. by thermolysis.

[0021] By "sulfur compound", it is meant a compound containing one or more sulfur atoms. In one embodiment, the sulfur compound is a thiol, a thio-ether, or a thioacid.

[0022] According to the present invention, the liquid sample is an additive for the oil industryselected from a corrosion inhibitor, an oil wetting agent, a solid dispersing agent, a scale inhibitor, an anti-foulant, an oxygen scavenger, a foaming agent, or a mixture thereof. These additives are commonly formulated as liquid blends of various chemical compounds, including sulfur compounds such as thiols or thioethers. But the method of the invention is not limited to these additives and can be applied to any liquid composition able to release gaseous H2S under storage conditions.

[0023] By "liquid sample" or "liquid composition", it is meant a sample or composition which is liquid under normal conditions of use and storage, i.e. under atmospheric pressure and at 25 °C.

[0024] By "H2S release capacity", it is meant the amount of H2S released by a given amount of sample during a given period of time for a given temperature, under atmospheric pressure.

[0025] The method of the invention enables determining the amount of H2S which is released by a sample under conditions which simulate the real conditions under which the sample is stored.

[0026] Alternatively, the method of the invention can be used to screen and compare the H2S release capacity of various samples, and to select the one which has the lowest H2S release capacity. In that case, the quantitative analysis of the H2S release capacity is not necessary.

[0027] According to step a), a volume of the liquid sample is placed in a purge vessel so as to obtain a liquid phase and a gaseous phase in the flask.

[0028] In order to implement the method of the invention, a dynamic headspace technique, such as a Purge and Trap device, can be utilized.

[0029] Purge and Trap devices are typically used for extracting volatile organic compounds (VOCs) from a solid or a liquid matrix. They are generally combined with an analysis system for analyzing the desorbed compounds, such as a Gas Chromatograph.

[0030] Figure 1 represents a Purge and Trap device coupled to a Gas Chromatograph/Mass Spectrometer (GC/MS). The Purge and Trap device mainly consists of two pieces of equipment: an oven 1 having a gas inlet and a gas outlet and a trapping and desorbing unit 2 in fluid communication with the oven 1. The oven 1 is configured to receive the purge vessel 3 containing the liquid sample to be analyzed. A flow of inert gas 4 is then introduced in the oven 1 through the gas inlet to purge the oven atmosphere at a constant flow rate for a determined time (purging step). This way, the inert gas stream makes contact with the sample. This process allows the inert gas stream to strip the gaseous H2S released from the sample matrix through the gas outlet of the oven 1 and to concentrate it on a H2S trap of the trapping and desorbing unit 2. Once the purging step is over, all the trapped molecules are desorbed and sent to the GC/MS 5 and 6 for analysis, as described in more details below.

[0031] In one embodiment, the liquid phase and the gaseous phase are obtained by ageing the liquid sample in the purge vessel at a given temperature.

[0032] Additives for the oil industry are usually stored on the petroleum site and thus can be exposed to relatively high temperatures (from 40°C to 50°C), especially when the petroleum site in a hot country. Therefore, the purge vessel may require to be heated in order to reproduce the storage conditions.

[0033] Typically ageing of the liquid sample is performed by heating the purge vessel at a temperature from 40°C to 60°C, more particularly from 45°C to 55°C, during a period of time ranging from 1 min to 30 min, in particular from 2 min to 10 min, more particularly from 4 min to 6 min.

[0034] If the purge vessel is not heated, the amount of H2S released from the liquid sample may be too low for being easily analyzed.

[0035] In one embodiment, the volume of liquid sample placed in the purge vessel is from 1 µL to 300 µL, in particular from 5 µL to 100 µL.

[0036] According to the invention, the gaseous phase in then purged with an inert gas stream for a determined period of time (step b) and the purged gaseous phase is passed through a H2S trap (step c).

[0037] The flow rate of the inert gas stream for the purge and trap of steps b) or c) can be from 20 mL/min to 90 mL/min, in particular from 50 mL/min to 70 mL/min.

[0038] The inert gas is preferably chosen from helium, nitrogen, or hydrogen. When the Purge and Trap device is coupled to a Gas Chromatograph, the inert gas is preferably the same as the one used in the Gas Chromatograph, typically helium.

[0039] According to the invention, during the purging step b), the purge vessel is kept at a temperature from 40°C to 60°C. The purge vessel may more particularly be kept at a temperature from 45°C to 55°C.

[0040] The duration of the purging step b) can be performed during a period of time ranging from 1 min to 30 min, in particular from 2 min to 10 min, more particularly from 4 min to 6 min.

[0041] In practice, the temperature of the purge vessel and the flow rate of the inert gas are adjusted so that the duration of the purging step b) is only a few minutes, thereby allowing a rapid screening of a large number of liquid samples.

[0042] In a preferred embodiment, the operating conditions are the following ones:
  • volume of the liquid sample: from 5 µL to 100 µL,
  • temperature of the purge vessel is from 45°C to 55°C, preferably around 50°C,
  • duration of the purging step b): from 4 min to 6 min, around 5 minutes,
  • flow rate of the inert gas: from 50 mL/min to 70 mL/min, preferably around 60 mL/min.


[0043] The purged gaseous phase that contains H2S released from the sample is passed through the H2S trap where it is concentrated (step c).

[0044] The H2S trap may be any device which is able to retain gaseous H2S during the entire purging step and then to rapidly release it during the recovery step d).

[0045] The concentration of H2S on the H2S trap may be performed by cryofocusing, adsorption, absorption, gas-solid reaction with a captation mass, in particular by cryofocusing on a polymeric non-polar adsorbent such as Tenax® adsorbent.

[0046] Cryofocusing is a technique that can rapidly and specifically trap all the H2S contained in the gaseous phase. It can be performed with liquid nitrogen.

[0047] In one embodiment, cryofocusing is performed at a temperature below the H2S condensing temperature (-85.7°C) but above the inert gas condensing temperature so that only H2S is trapped by cryofocusing. The cryofocusing can performed at a temperature from -150°C to - 50°C, more particularly from -125°C to -60°C, even more particularly from -105°C to - 86°C.

[0048] Alternatively, H2S can be trapped by asorbent material. By "sorbent material", it is meant any solid which is able to selectively adsorb or absorb H2S such as ZnO, CuO, Cu2O, MoO3..

[0049] The trapped H2S is then recovered from the H2S trap (step d)). Any suitable method can be used. For instance, H2S can be recovered by thermo-desorption if cryofocalisation is used to trap H2S.

[0050] Thermo-desorption is typically performed by passing an inert gas stream through the H2S trap while heating said H2S trap.

[0051] Typically, the flow rate of the inert gas stream during the thermo-desorption is below 5 mL/min, in particular from 0.1 mL/min to 3 mL/min, more particularly from 0.5 mL/min to 2 mL/min.

[0052] Typically, the H2S trap is heated from temperature T1 to temperature T2, wherein T2 is higher than T1, at a heating rate from 1°C/s to 50°C/s, in particular from 5°C/s to 20°C/s, more particularly from 10°C/s to 15°C/s.

[0053] Typically T1 is from 50°C to 150°C, in particular from 75°C to 125°C, more particularly from 90°C to 110°C. Typically T2 is from 250°C to 350°C, in particular from 275°C to 325°C, more particularly from 290°C to 310°C.

[0054] The recovered H2S is then measured in the measuring step e). Any suitable analytical method can be used.

[0055] The measuring step e) can be performed for instance by gas chromatography possibly coupled with mass spectrometry, thermogravimetric analysis possibly coupled with mass spectrometry, elemental analysis for sulfur.

[0056] Preferably, the measuring step e) is performed by gas chromatography coupled with mass spectrometry.

[0057] The measurement can be quantitative or semi-quantitative. A semi-quantitative measurement does not require the time consuming step of calibration.

[0058] When the measurement is quantitative, the amount of H2S released by a given amount of sample during a given period of time for a given temperature, under atmospheric pressure can be quantitatively determined.

[0059] When the measurement is semi-quantitative, the method of the invention can be used to compare the H2S release capacity of various liquid samples one to each other (screening method). In that case, no calibration is required. For instance, when a gas chromatography coupled with mass spectrometry is used for the measuring step e), the H2S release capacity is expressed as a peak-area.

[0060] Another object of the present invention is a method for selecting one or more liquid samples among a group of different liquid samples, said method comprising the following steps:
  • Assessing the H2S release capacity of each liquid sample according to the method as defined previously;
  • Selecting one or more liquid samples which have the lowest H2S release capacity.


[0061] This method can be used for instance to identify the liquid sample which has the lowest H2S release capacity among a group of liquid samples. After assessing the H2S release capacity of each liquid sample, the samples can be sorted out according to their H2S release capacity. But this step is not mandatory.

[0062] Another object of the present invention is a method for selecting a liquid sample, said method comprising the following steps:
  • Assessing the H2S release capacity of each liquid sample according to the method as defined previously;
  • Comparing the H2S release capacity with a threshold value.


[0063] This method can be used for instance to compare a liquid sample with a reference product or a standard (threshold value).

[0064] The methods of the invention can be performed utilizing commercially available devices. Therefore, they are easy to carry out. They can be quantitative or semi-quantitative, and they are fast and effective.

[0065] The following examples provide another illustration of the invention but without restraining to the scope of the invention.

Examples


Example 1: apparatus and method



[0066] A thermal desorption instrument (TDU, Gerstel) is used with a cooled injection system (CIS-4, Gerstel). The cooled injection system is linked to a gas chromatograph (Agilent, 6890N) coupled to a mass spectrometer (Micro Quattro, Waters). The detection is made in the ionization mode by electronic impact, in mode SIM positif at m/z = 34.

[0067] As an illustration, a single sulfur containing sample is used as an example to demonstrate the quantitative aspect of the method. The sulfur containing sample tested is thioglycol acid (TGA). Different volumes of TGA are tested (10, 20, 30, 40 and 50 µl) in the thermal desorption instrument 1. Each volume is aged at 50°C, during 5 minutes. A sweeping inert gas (helium, flow rate: 60 mL/min) sweeps the H2S formed to the cooled injection system 2 wherein H2S is trapped by cryofocusing, thanks to liquid nitrogen (-100°C). Once the ageing is finished, the quantity of trapped H2S is analyzed by the gas chromatograph 3 and the mass spectrometer 4.

Example 2: Results



[0068] Figure 2 shows the area of the peak of H2S obtained by GC/MS as a function of the volume of sample. The area of the peak of H2S is proportional to the amount of TGA tested.

[0069] Other samples may be tested under the same conditions. By comparing the area of the peak of H2S of each sample, one can easily determine which sample has the lowest H2S release capacity among the group of samples (screening method).

[0070] These results show that the method of the invention enables the rapid and efficient assessment of the H2S release capacity of liquid sulfur containing samples.


Claims

1. A method for assessing the H2S release capacity of a liquid sample containing one or more sulfur compounds which are able to be degraded into gaseous H2S with temperature, said method comprising the following steps:

a) Placing a volume of the liquid sample in a purge vessel (3) so as to obtain a liquid phase and a gaseous phase in a flask;

b) Purging the gaseous phase with an inert gas stream for a determined period of time;

c) Passing the purged gaseous phase through a H2S trap;

d) Recovering H2S from the H2S trap;

e) Measuring the recovered H2S,

wherein the purge vessel (3) is kept at a temperature from 40°C to 60°C, characterised in that the liquid sample is a corrosion inhibitor, an oil wetting agent, a solid dispersing agent, a scale inhibitor, an anti-foulant, an oxygen scavenger, a foaming agent, or a mixture thereof.
 
2. The method according to claim 1, wherein the sulfur compound is a thiol, a thio-ether or a thioacid.
 
3. Method according to claim 1 or 2, wherein the liquid sample has a boiling temperature of at least 80°C.
 
4. The method according to any one of claims 1 to 3, wherein the purge vessel (3) is kept at a temperature from 45°C to 55°C.
 
5. The method according to any one of claims 1 to 4, wherein the flow rate of the inert gas stream during steps b) or c) is from 20 mL/min to 90 mL/min, in particular from 50 mL/min to 70 mL/min.
 
6. The method according to any one of claims 1 to 5, wherein the inert gas is chosen from helium, nitrogen or hydrogen.
 
7. The method according to any one of claims 1 to 6, wherein the period of time of the purging step b) is from 2 min to 12 min, in particular from 3 min to 10 min, more particularly from 5 min to 8 min.
 
8. The method according to any one of claims 1 to 7, wherein the trapping step c) is performed by cryofocusing, adsorption, absorption, gas-solid reaction with a captation mass, in particular by cryofocusing on polymeric non-polar adsorbent with liquid nitrogen.
 
9. Method according to any one of claims 1 to 8, wherein the measuring step e) is performed by gas chromatography (5) possibly coupled with mass spectrometry (6), thermogravimetric analysis possibly coupled with mass spectrometry (6), elemental analysis for sulfur, in particular by gas chromatography (5) coupled with mass spectrometry (6) .
 
10. A method for selecting a liquid sample among a group of different liquid samples, said method comprising the following steps:

- Assessing the H2S release capacity of each liquid sample according to the method as defined in any one of claims 1 to 9;

- Selecting the sample which has the lowest H2S release capacity.


 
11. A method for selecting a liquid sample, said method comprising the following steps:

- Assessing the H2S release capacity of each liquid sample according to the method as defined in any one of claims 1 to 9;

- Comparing the H2S release capacity with a threshold value.


 


Ansprüche

1. Verfahren zur Beurteilung der H2S-Freisetzungskapazität einer flüssigen Probe, die eine oder mehrere Schwefelverbindungen enthält, die in gasförmiges H2S mit Temperatur abgebaut werden können, wobei das Verfahren die folgenden Schritte umfasst:

a) Platzieren eines Volumens der flüssigen Probe in ein Spülgefäß (3), um eine flüssige Phase und eine gasförmige Phase in einem Kolben zu erhalten;

b) Spülen der gasförmigen Phase mit einem Inertgasstrom für einen bestimmten Zeitraum;

c) Durchleiten der gespülten gasförmigen Phase durch eine H2S-Falle;

d) Zurückgewinnen von H2S aus der H2S-Falle;

e) Messen des zurückgewonnenen H2S,

wobei das Spülgefäß (3) bei einer Temperatur von 40°C bis 60°C gehalten wird, dadurch gekennzeichnet, dass
die flüssige Probe ein Korrosionsinhibitor, ein Ölbenetzungsmittel, ein Feststoff-Dispergiermittel, ein Kesselstein-Inhibitor, ein Antifouling-Mittel, ein Sauerstofffänger, ein Schaummittel oder eine Mischung davon ist.
 
2. Verfahren nach Anspruch 1, wobei die Schwefelverbindung ein Thiol, ein Thio-ether oder eine Thiosäure ist.
 
3. Verfahren nach Anspruch 1 oder 2, wobei die flüssige Probe eine Siedetemperatur von mindestens 80°C aufweist.
 
4. Verfahren nach einem der Ansprüche 1 bis 3, wobei das Spülgefäß (3) bei einer Temperatur von 45°C bis 55°C gehalten wird.
 
5. Verfahren nach einem der Ansprüche 1 bis 4, wobei die Strömungsgeschwindigkeit des Inertgasstroms während der Schritte b) oder c) von 20 ml/min bis 90 ml/min, bevorzugt von 50 ml/min bis 70 ml/min, beträgt.
 
6. Verfahren nach einem der Ansprüche 1 bis 5, wobei das Inertgas ausgewählt ist aus Helium, Stickstoff oder Wasserstoff.
 
7. Verfahren nach einem der Ansprüche 1 bis 6, wobei der Zeitraum des Spülschritts b) von 2 min bis 12 min, bevorzugt von 3 min bis 10 min, stärker bevorzugt von 5 min bis 8 min beträgt.
 
8. Verfahren nach einem der Ansprüche 1 bis 7, wobei der Einfangschritt c) durch Kryofokussierung, Adsorption, Absorption, Gas-Feststoff-Reaktion mit einer Einfangmasse, bevorzugt durch Kryofokussierung auf polymerem unpolarem Adsorptionsmittel mit flüssigem Stickstoff durchgeführt wird.
 
9. Verfahren nach einem der Ansprüche 1 bis 8, wobei der Messschritt e) durch Gaschromatographie (5), ggf. gekoppelt mit Massenspektrometrie (6), thermogravimetrischer Analyse, ggf. gekoppelt mit Massenspektrometrie (6), Elementaranalyse auf Schwefel, bevorzugt durch Gaschromatographie (5) gekoppelt mit Massenspektrometrie (6) durchgeführt wird.
 
10. Verfahren zur Auswahl einer flüssigen Probe aus einer Gruppe von unterschiedlichen flüssigen Proben, wobei das Verfahren die folgenden Schritte umfasst:

- Bestimmen der H2S-Freisetzungskapazität von jeder flüssigen Probe gemäß dem Verfahren wie in einem der Ansprüche 1 bis 9 definiert;

- Auswählen der Probe, die die geringste H2S-Freisetzungskapazität aufweist.


 
11. Verfahren zur Auswahl einer flüssigen Probe, wobei das Verfahren die folgenden Schritte umfasst:

- Bestimmen der H2S-Freisetzungskapazität von jeder flüssigen Probe gemäß dem Verfahren wie in einem der Ansprüche 1 bis 9 definiert;

- Vergleichen der H2S-Freisetzungskapazität mit einem Schwellenwert.


 


Revendications

1. Procédé pour évaluer la capacité de libération de H2S d'un échantillon liquide contenant un ou plusieurs composés soufrés qui sont capables de se dégrader en H2S gazeux avec la température, ledit procédé comprenant les étapes suivantes :

a) le placement d'un volume de l'échantillon liquide dans un récipient de purge (3) de manière à obtenir une phase liquide et une phase gazeuse dans un flacon ;

b) la purge de la phase gazeuse avec un flux de gaz inerte pendant une période de temps déterminée ;

c) le passage de la phase gazeuse purgée à travers un piège à H2S ;

d) la récupération du H2S à partir du piège à H2S ;

e) la mesure du H2S récupéré,

dans lequel le récipient de purge (3) est maintenu à une température de 40 °C à 60 °C, caractérisé en ce que
l'échantillon liquide est un inhibiteur de corrosion, un agent de mouillage d'huile, un agent de dispersion de solide, un inhibiteur de tartre, un agent antisalissure, un absorbeur d'oxygène, un agent moussant, ou un mélange de ceux-ci.
 
2. Procédé selon la revendication 1, dans lequel le composé soufré est un thiol, un thio-éther ou un thioacide.
 
3. Procédé selon la revendication 1 ou 2, dans lequel l'échantillon liquide présente une température d'ébullition d'au moins 80 °C.
 
4. Procédé selon l'une quelconque des revendications 1 à 3, dans lequel le récipient de purge (3) est maintenu à une température de 45 °C à 55 °C.
 
5. Procédé selon l'une quelconque des revendications 1 à 4, dans lequel le débit du flux de gaz inerte pendant les étapes b) ou c) est de 20 ml/min à 90 ml/min, en particulier de 50 ml/min à 70 ml/min.
 
6. Procédé selon l'une quelconque des revendications 1 à 5, dans lequel le gaz inerte est choisi parmi l'hélium, l'azote ou l'hydrogène.
 
7. Procédé selon l'une quelconque des revendications 1 à 6, dans lequel la période de temps de l'étape de purge b) est de 2 min à 12 min, en particulier de 3 min à 10 min, plus particulièrement de 5 min à 8 min.
 
8. Procédé selon l'une quelconque des revendications 1 à 7, dans lequel l'étape de piégeage c) est effectuée par cryofocalisation, adsorption, absorption, réaction gaz-solide avec une masse de captation, en particulier par cryofocalisation sur adsorbant polymère non polaire avec de l'azote liquide.
 
9. Procédé selon l'une quelconque des revendications 1 à 8, dans lequel l'étape de mesure e) est effectuée par chromatographie en phase gazeuse (5) éventuellement couplée à une spectrométrie de masse (6), analyse thermogravimétrique éventuellement couplée à une spectrométrie de masse (6), analyse élémentaire du soufre, en particulier par chromatographie en phase gazeuse (5) couplée à une spectrométrie de masse (6).
 
10. Procédé pour sélectionner un échantillon liquide parmi un groupe d'échantillons liquides différents, ledit procédé comprenant les étapes suivantes :

- l'évaluation de la capacité de libération de H2S de chaque échantillon liquide selon le procédé tel que défini dans l'une quelconque des revendications 1 à 9 ;

- la sélection de l'échantillon qui présente la plus faible capacité de libération de H2S.


 
11. Procédé pour sélectionner un échantillon liquide, ledit procédé comprenant les étapes suivantes :

- l'évaluation de la capacité de libération de H2S de chaque échantillon liquide selon le procédé tel que défini dans l'une quelconque des revendications 1 à 9 ;

- la comparaison de la capacité de libération de H2S à une valeur seuil.


 




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REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description




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