The technical field of the invention is that the devices and methods used for measuring the concentration of hydrogen sulphide in a gaseous effluent, particularly where the gaseous effluent is from a reactor used for hydrotreating of petroleum products .

ART ANTERIEUR

Hydrotreating is a process mainly used in oil refining and which is intended to remove impurities such as sulfur contained in petroleum fractions from the distillation of crude oil. A hydrotreating unit comprises a reactor comprising two supply conduits, one for the introduction of the petroleum cut and the other to the pressurized hydrogen introduction. The reactor contains a catalyst which facilitates the transformation of sulfur compounds to hydrogen sulphide H 2 S.

In such a process, it is necessary to sulfide the hydrotreating catalyst which is, most often sold in an inactive form consisting of metal oxides of Group 6 metals combined with metals of Groups 9 and / or 10, these oxides are supported on a porous solid, such as an alumina. This sulfurization operation takes place in each catalyst change and is intended to convert the metal oxides into sulfides which are the active species in the hydrotreating reaction. To do this, it is known to contacting the catalyst with a sulfur source, such as dimethyl disulfide (DMDS). Under the effect of high temperature and high pressure, dimethyl disulphide is decomposed to hydrogen sulphide which reacts with the catalyst to form the desired metal sulfides. Detection of hydrogen sulfide formed during the sulphurization of the catalyst is necessary because it allows to have an estimate of the degree of completion of the sulfurization reaction. On the other hand, it is desirable to minimize the amount of hydrogen sulfide emitted during the sulfurization reaction. In addition, measuring the concentration of hydrogen sulphide is currently performed by the staff of the refineries, at best hourly, in conditions of security that can be dangerous, especially because of the toxicity of hydrogen sulfide ( H 2 S). It was therefore sought a device and a technique that allows a reliable measurement, more frequent, in enhancing safety.

There are devices for measuring on-line concentration of hydrogen sulfide in gaseous effluents from units performing the oxidation of sulfur to hydrogen sulfide, called Claus units. These are for example described in documents FR 2,778,743 and FR 2 944 456. However, these devices are designed to be permanently mounted on the installation generating the effluent containing the hydrogen sulfide. They can not be easily removed for use on another fast Claus unit.

The document CN 203595659U describes a device for measuring the concentration of hydrogen sulfide in a gas stream whose operating principle is based on a laser spectroscopic analysis. However, this device requires the use of an inerting gas laser equipment, that is to say, a gas that is not combustion with the gas to be analyzed and that makes it anti-explosive measuring device. However, the use of an inert gas makes the device complex.

therefore sought a measuring device which can be easily transported from one site to another and does not require the use of an inert gas.

US 8,163,242 describes a measurement of the concentration of chemical species device contained in the gases from the decomposition of waste in landfills. However, this document provides no information on the technique used to specifically measure the concentration of hydrogen sulfide. In addition, this measuring device seems to appeal to an electrochemical technique, which is not suitable for high concentrations of steps without using a dilution gas. The analysis of this paper material is "a chemical analyzer," which in principle involves an irreversible chemical reaction, so frequent replacement of chemical sensors.

WO 2014/144038 discloses a real-time measurement device of the concentration of hydrogen sulfide in a hydrotreating unit of petroleum products. This device is transported and connected temporarily to the outlet conduit of the hydrotreating unit. Preferably, the measure is based on the chemical reaction between lead acetate and hydrogen sulfide. Of lead acetate is deposited on a strip of paper, giving a white color to the band. During the chemical reaction, forms the black lead sulfide. The degree of blackness of the paper web is proportional to the amount of hydrogen sulfide passed through the measuring system. This measurement system nevertheless has the following disadvantages:

- It requires a diffusion chamber intended to be diluted, for example with nitrogen, gas of which we wish to measure the concentration of hydrogen sulfide. The dilution gas can either be from a local network or be brought with the portable analyzer.

The use of nitrogen from a refinery can result in error analysis because of pollution from processes used in the refinery.

- Replacement of worn paper with new paper impregnated by lead acetate is performed by an operator. However, party lead acetate carcinogenic chemicals and / or mutagenic and / or toxic for reproduction (Substances "CMR"). Each change paper exposes the operator to contact with lead acetate, which presents a risk her health.

- This device does not allow to maintain a good measurement accuracy of the concentration of H 2 S in time, over a wide concentration range from 0 to 30,000 ppm.

This document also indicates that the detection of hydrogen sulphide can be performed by an electrochemical method.

The document CN 101782514 discloses a device for measuring the concentration of hydrogen sulfide in natural gas, before and after desulfurization. Said device comprising a fixedly installed on an installation part in which the gas containing H 2 S is circulated, and a removable portion that can be connected to this fixed part. The fixed portion comprises:

- a measuring chamber in which is performed a measurement of the absorption by the gas of laser radiation;

- a pressure gauge and an expansion valve for regulating the pressure of the sample gas to the working pressure of the measuring chamber.

The removable portion comprises:

- a device for producing laser radiation and

- a device processing the optical signal from the measuring chamber.

This part is removable since it may connect to the fixed part by means of two optical fibers. Therefore, herein, only the part dedicated to the production of laser radiation and the signal processing is removable.

therefore sought for a long time in the prior art to provide a transportable device accurate continuous measurement of the concentration of hydrogen sulfide from a gaseous effluent, generally between 100 ppm and 50,000 ppm by volume, preferably between 100 ppm and 30,000 ppm, which can be connected temporarily to a duct for transporting the offgas and not using dilution gas. Preferably, this device does not require the use of chemicals

dangerous such as, inter alia, the "CMR" (carcinogenic mutagens Reprotoxic). More preferably, this device does not require a supply of an inert gas.

SUMMARY OF THE INVENTION

The invention relates to a kit for measuring the concentration of hydrogen sulfide from a gas capable of containing, said kit comprising separate modules and connectable to each other, said modules being:

- a measurement module A comprising a measuring chamber in which M is performed the measurement of the absorption by the gas of a monochromatic electromagnetic radiation; - a trigger module B for bringing the pressure of the sample gas to the working pressure of the measuring module;

- a pressure regulator module C adapted to maintain the gas pressure in the measuring chamber to a value within the range of working pressure values ​​from the measuring module;

- a D operating module of the absorption measurement, to obtain the concentration of hydrogen sulfide in the gas, and

- the means to connect the modules together.

The gas which is desired to measure concentration of hydrogen sulfide is generally flammable.

According to one embodiment, the electromagnetic radiation is infrared radiation fixed wavelength emitted by a laser, preferably at a wavelength between 780 nm and 3000 nm.

According to one embodiment, the electromagnetic radiation is monochromatic radiation in the ultraviolet range of wavelengths of visible or, preferably in the area of ​​wavelengths between 100 nm and 380 nm, or between 380 and 780 nm, respectively.

According to one embodiment,

- the expansion unit B has an inlet conduit (2) receiving the gas to be analyzed and an outlet conduit (3) connected to an inlet conduit (4) of the measuring module A;

- the measurement unit A is electrically connected (9) to D operating module;

- the control unit C is connected mechanically to the measurement module A (5, 7) and a discharge pipe (8) of the gas outwardly from the kit.

According to one embodiment, the expansion module B makes it possible to bring the pressure of the gas to be analyzed in the measuring module working pressure between 500 hPa (0.5 bar) and 2000 hPa (2 bar) related.

According to one embodiment,

- the measurement unit A has a mass less than or equal to 60 kg, preferably less than or equal to 55 kg, preferably less than or equal to 50 kg;

- B expansion module has a mass less than or equal to 20 kg, preferably less than or equal to 15 kg, preferably less than or equal to 10 kg;

- the control unit C has a mass less than or equal to 20 kg, preferably less than or equal to 15 kg, preferably less than or equal to 10 kg;

- D operating module has a mass less than or equal to 50 kg, preferably less than or equal to 40 kg, preferably less than or equal to 35 kg;

The kit can be used for measuring the concentration of hydrogen sulfide from a gas capable of containing said gas comprising at least 50% hydrogen by volume. The gas may contain hydrogen sulfide can be a gaseous effluent from a reactor used for the purification of hydrocarbons from refining processes or derived from petrochemicals.

The invention also relates to a continuous method for measuring the concentration of hydrogen sulfide from a gaseous effluent by means of a removable device adapted to be connected temporarily to an installation producing said gaseous effluent, the method comprising a step of measuring the absorption by the gaseous effluent of a monochromatic electromagnetic radiation. The measurement method may use the kit as described above, measuring the hydrogen sulfide concentration is performed after fitting of the kit Facility. At the end of operation, the removable device can be easily disassembled for installation and reduced as a kit and then be reassembled on another facility in which the same type of measurement to be made.

According to one embodiment, the electromagnetic radiation is infrared radiation fixed wavelength emitted by a laser, preferably at a wavelength between 780 nm and 3000 nm.

According to one embodiment, the electromagnetic radiation is monochromatic radiation in the ultraviolet range of wavelengths of visible or, preferably in the area of ​​wavelengths between 100 nm and 380 nm, or between 380 and 780 nm, respectively.

According to one embodiment, the continuous method for measuring the concentration of hydrogen sulfide gas comprises a likely implementation, as a device, the kit according to the invention.

According to one embodiment, the gas is a gaseous effluent from a reactor used for the purification with hydrogen to hydrocarbons from refinery processes or derived from petrochemicals.

According to one embodiment, the method is used to monitor progress and / or to ensure that the end of sulfurization step of a hydrotreating catalyst.

Finally, the invention relates to an installation in which a gas stream containing hydrogen sulphide is likely to be generated, characterized in that it incorporates a device obtained by mounting the kit according to the invention.

DESCRIPTION OF THE FIGURE

Figure 1 shows schematically according to one embodiment of the invention connecting the device according to the invention the output of a hydrotreating unit and the connections of the various modules.

EMBODIMENTS DESCRIPTION OF THE INVENTION

The device according to the invention is in the form of a kit comprising separate modules and connectable to each other, said modules being:

- a measurement module A comprising a measuring chamber in which M is performed the measurement of the absorption by the gas of electromagnetic radiation;

- a trigger module B for bringing the pressure of the sample gas to the working pressure of the measuring module;

- a pressure regulator module C adapted to maintain the gas pressure in the measuring chamber to a value within the range of working pressure values ​​from the measuring module;

- an operating unit D of the extent of absorption, for obtaining the concentration of hydrogen sulfide in the gas, and

- the means to connect the modules together.

The description of the arrangement of the different modules of the kit according to one embodiment of the invention is given with reference to Figure 1.

A measuring module comprises an inlet conduit (4) adapted to be mechanically connected to the outlet duct (3) of the expansion module B and an outlet conduit (5)

adapted to be mechanically connected to a conduit (7) of the control unit C. The measurement of the concentration of hydrogen sulphide is carried out in a measuring chamber M according to the known principle of spectrophotometry. According to this principle, a substance is traversed by electromagnetic radiation and measuring absorption of the electromagnetic radiation by the substance. This measurement chamber consists of a capacity stainless steel, generally tubular and of a length between 5 and 80 cm, preferably between 10 and 50 cm. This measurement chamber comprises an emitting source of electromagnetic radiation and a radiation sensor that converts the radiation into an electrical signal. Emitting diode and the sensor can be fixed on the walls of the measuring cell one opposite the other or side by side. In the latter case, the electromagnetic radiation is reflected on a mirror which reflects the radiation towards the sensor. This configuration increases the optical path and the measurement sensitivity. The choice of either configuration depends on the wavelength of the electromagnetic radiation and the radiation absorption coefficient with hydrogen sulfide, as well as the measuring range of the concentration of chosen hydrogen sulphide. Optionally, the source of electromagnetic radiation and the sensor may be transported to the measuring chamber by adding two optical fibers to cause the electromagnetic radiation from the source to the measuring chamber and bring the same radiation, after absorption, to the sensor.

Electromagnetic radiation can be:

- a laser light emitting in the infrared at a fixed wavelength between 780 and 3000 nm;

- a monochromatic electromagnetic radiation emitting in the ultraviolet range or the visible range, that is to say in the area of ​​wavelengths between 100 nm and 380 nm, or between 380 and 780 nm, respectively.

You can use an infrared laser analyzer: Model "SS2100 TDL Gas Analyzer" sold by Spectra Sensor Company or a UV analyzer Visible Model "OMA-300 hydrogen sulfide Analyzer" sold by Applied Analytics Company.

A module generally has a mass less than or equal to 60 kg, preferably less than or equal to 55 kg, preferably less than or equal to 50 kg.

The trigger module B comprises:

- an inlet conduit (2) adapted to be mechanically connected to the duct (1) itself mounted as a branch of the outlet pipe of gases from a hydrotreating reactor.

- an outlet conduit (3) adapted to be mechanically connected to the inlet conduit (4) of the measuring module A. Its function is to reduce the gas pressure to the working pressure of the measurement module which is generally between 500 hPa and 2000 hPa.

- optionally an outlet duct (10) for discharging a pressure not compatible with the operating pressure of the measurement module which is generally between 500 hPa and 2000 hPa. He plays the role of security organ.

The B trigger module generally has a mass less than or equal to 20 kg, preferably less than or equal to 15 kg, preferably less than or equal to 10 kg

The control unit C has an inlet conduit (6) adapted to be optionally mechanically connected to the conduit (10) and two ducts (7,8). One of the two ducts (8) is a gas exhaust duct or for feeding gas to a gas destruction device, such as a torch providing the combustion gas. The other pipe (7) is adapted to receive the gas from the module A measurement gas to be analyzed. The control module can control the pressure in the module measuring chamber A to a value within the range of work of the measuring module pressures. If the pressure is less than the lower limit of the range of working pressures, the expansion module B sends the gas in the measuring chamber via the conduit (3). If it exceeds the upper limit of the range of operating pressures, gas is injected into the conduit (10) and (8) discharge or destruction of the gas. The conduit (8) also receives the gas from the measuring module A when the latter is operating in the working pressure range.

The control unit C typically has a mass less than or equal to 20 kg, preferably less than or equal to 15 kg, preferably less than or equal to 10 kg.

The module operating D spectroscopic signal is electrically connected to the module B through the electrical connection (9). It converts the measurement of the absorption from module A in a concentration of hydrogen sulfide. In a preferred embodiment of the invention, the instantaneous content of hydrogen sulfide may be indicated by display, advantageously integrated to the module D.

D operating module generally has a mass less than or equal to 50 kg, preferably less than or equal to 40 kg, preferably less than or equal to 35 kg.

The analysis results generated by the operating module D can be transferred during or after analysis, in whole or in part, to a computer via a wireless transmission for example of WiFi, Bluetooth, and other, or a wired transmission by means of a memory card.

A and D modules may be each contained in a thick metal flameproof enclosure as defined in the standard 94/9 / EC, that is to say that any explosion remains confined within the casing which is damage.

The gaseous effluent containing hydrogen sulfide to be analyzed can be derived from a hydrotreating reactor HDT. The effluent gas typically contains between 100 and 50,000 ppm by volume of hydrogen sulphide, preferably between 100 and 30,000 ppm by volume, more preferably between 1000 and 20,000 ppm by volume.

Upon exiting the hydrotreating reactor, the gaseous effluent rich in hydrogen is separated from the liquid hydrocarbons in a vessel wherein the liquid compounds accumulate Length whereas the non-condensable gases are discharged and head. These gases are, in general, recompressed by a compressor to be reinjected upstream of the hydrotreating reactors. These gases constitute the gaseous effluent which is desired to determine the content of hydrogen sulfide. For this purpose, instead bypassing the main gas stream, a circuit completed by a connecting duct (1). This conduit (1) is connected to the conduit (2) module input B. The gas to be analyzed is fed into the expansion module B with the inlet duct (2) and is transferred through the outlet duct ( 3) in the measuring module A comprising the measuring chamber M. It is then sent to the control unit C. It is discharged from the control unit C and is sent to the torch (T) to be burned therein. The control unit C maintains the gas pressure in the measuring module at a constant value by adjusting the amount of gas fed into the measuring chamber M and the pressure directed to the torch T. In the case where the gas to be analyzed would be in duct (1) at a pressure compatible with the operating pressure of the measuring module a, the expansion module is optional.

The connections between the modules A, B and C as well as to connect to the gas sampling point (1) and the discharge circuit by the torch T is carried out by flexible hoses capable of withstanding a maximum pressure of 25 MPa. They are equipped with quick connectors and plugs designed to be connected and disconnected frequently.

D module is connected to module A by electric cables.

According to one embodiment, the modules A and D are fixed in a common housing to which are connected the modules B and C.

According to one embodiment, the A and C modules are integral in a common housing to which are connected the modules B and D.

According to one embodiment, the modules A, C and D are fixed in the same casing which is connected the module B.

The device of the invention can be easily connected without open circuit, which limits the risk of exposure of an operator to hazardous gas.

As part of the sulphurization of hydrotreating catalyst, DMDS perform injection at a rate requested by the refinery throughout the catalyst activation procedure, which usually takes 1 to 2 days, and simultaneously with the injection DMDS is used the device of the invention for measuring and monitoring the increase in the concentration of hydrogen sulfide over time. When the concentration of hydrogen sulfide as compared to the amount of injected DMDS, shows that there is more sulfur determined by the catalyst, then there is no longer necessary to continue injecting DMDS.

The device according to the invention has the following advantages:

a) can be disconnected from the installation generating the gaseous effluent containing hydrogen sulfide after the measurement of the concentration has been carried out and it can be quickly transported to another site to be used there. The device according to the invention is characterized in that it is easily transportable by truck, plane, car or boat, due to its low weight (eg 2 modules of less than 50 kg each and two units under 10 kg each) and by its reduced dimensions, that is to say generally less than 800 mm x 600 mm x 400 mm. It can also be carried by a man, without the latter having to resort to a handling device.

b) It is "autonomous" in that it does not require the use of any gas, other than the subject of the analysis. In particular :

- It requires no carrier gas, which is an advantage over measuring techniques by chromatography in the gaseous phase which require the use of hydrogen or helium.

- It does not necessarily require the use of an inert gas to conform to the ATEX (Explosive Atmospheres) on equipment for use in explosive atmospheres.

- It does not require the use of a dilution gas, unlike the electrochemical measurement techniques or by reaction between hydrogen sulfide and lead acetate, as mentioned in WO 2014/144038.

c) It is characterized by low measurement uncertainty (<100 ppm) over the entire desired measurement range for application to hydrotreating, unlike the techniques requiring a dilution gas, such as that based on the use of a paper impregnated with lead acetate.

d) It allows a continuous analysis of the concentration of hydrogen sulfide, with a measuring frequency lying in the range 5 to 30 seconds after the flow of gas to be analyzed. With this measurement continuously, the raffmeur can react more quickly to drifts of the content of hydrogen sulfide to adjust, for example, the injection rate of DMDS. This avoids high concentrations of hydrogen sulfide in excess of 3% by volume, adverse to the recompression section and too low concentrations, lower than 0.1%, which can damage the catalyst when the reactor temperature exceeds 250 ° C.

e) does not require the use of hazardous chemicals, such as lead acetate.

f) complies with ATEX (explosion proof European standard or explosion) while being both portable and compact. Indeed, we find in industrial analysis equipment suppliers as fixed and bulky equipment that meets the minimum standard for AT ex II 2 G Ex d IIB + H2T4. The ATEX classification of the equipment is based on the European Directive 94/9 / EC.

The kit according to the invention corresponds to the point "p" (elimination of the explosive atmosphere) of the ATEX classification and / or at the point "e" (elimination of the ignition source) and / or at point "d" ( flameproof, non propagation of inflammation). Preferably, the kit of the invention has at least to the point "d" of the ATEX classification by the use of explosion proof enclosures around the modules A and D.

The description of the invention has been made in the above by taking as an example the measurement of hydrogen sulphide in a gaseous effluent from a hydrotreating unit from petroleum fractions. However, the invention is not limited to this application and can be implemented in petroleum refining processes where hydrogen is used to purify hydrocarbons. It can also be implemented to measure the amount of hydrogen sulphide present in a gaseous effluent from a unit implementing the catalytic oxidation reaction of sulfur to hydrogen sulfide (Claus reaction). It can also be used in petrochemical products processing processes of natural origin ( "biorefinery"). It can also be implemented in the fields of industry producing hydrogen sulfide, such as waste water treatment, blast furnaces, paper, tannery.

CLAIMS

1. A kit for measuring the concentration of hydrogen sulfide from a gas capable of containing, said kit comprising separate modules and connectable to each other, said modules being:

- a measurement module A comprising a measuring chamber in which M is performed the measurement of the absorption by the gas of a monochromatic electromagnetic radiation;

- a trigger module B for bringing the pressure of the sample gas to the working pressure of the measuring module;

- a pressure regulator module C adapted to maintain the gas pressure in the measuring chamber to a value within the range of working pressure values ​​from the measuring module;

- a D operating module of the absorption measurement, to obtain the concentration of hydrogen sulfide in the gas, and

- the means to connect the modules together.

2. Kit according to claim 1, wherein the electromagnetic radiation is infrared radiation at fixed wavelength emitted by a laser, preferably at a wavelength between 780 nm and 3000 nm.

3. Kit according to claim 1, wherein the electromagnetic radiation is monochromatic radiation in the ultraviolet range of wavelengths of visible or, preferably in the area of ​​wavelengths between 100 nm and 380 nm, or between 380 and 780 nm, respectively.

4. Kit according to one of claims 1 to 3, wherein:

- the expansion unit B has an inlet conduit (2) receiving the gas to be analyzed and an outlet conduit (3) connected to an inlet conduit (4) of the measuring module A;

- the measurement unit A is electrically connected (9) to D operating module;

- the control unit C is connected mechanically to the measurement module A (5, 7) and a discharge pipe (8) of the gas outwardly from the kit.

5. Kit according to one of the preceding claims, wherein the expansion module B makes it possible to bring the pressure of the gas to be analyzed in the measuring module working pressure between 500 hPa (0.5 bar) and 2000 hPa (2 bar) related.

6. Kit according to one of the preceding claims, wherein:

- the measurement unit A has a mass less than or equal to 60 kg, preferably less than or equal to 55 kg, preferably less than or equal to 50 kg;

- B expansion module has a mass less than or equal to 20 kg, preferably less than or equal to 15 kg, preferably less than or equal to 10 kg;

- the control unit C has a mass less than or equal to 20 kg, preferably less than or equal to 15 kg, preferably less than or equal to 10 kg;

- D operating module has a mass less than or equal to 50 kg, preferably less than or equal to 40 kg, preferably less than or equal to 35 kg;

7. Method for continuously measuring the concentration of hydrogen sulfide from a gaseous effluent by means of a removable device adapted to be connected temporarily to an installation producing said gaseous effluent, the method comprising a step of measuring absorption by the gaseous effluent of a monochromatic electromagnetic radiation.

8. Method according to claim 7, wherein the electromagnetic radiation is infrared radiation at fixed wavelength emitted by a laser, preferably at a wavelength between 780 nm and 3000 nm.

9. Method according to claim 7, wherein the electromagnetic radiation is monochromatic radiation in the ultraviolet range of wavelengths of visible or, preferably in the area of ​​wavelengths between 100 nm and 380 nm, or between 380 and 780 nm, respectively.

10. Method for continuously measuring of the concentration of hydrogen sulfide from a gas capable of containing according to one of claims 7 to 9, comprising the implementation, as a device, the kit according to the one of claims 1 to 6.

11. Measuring method according to one of Claims 7 to 10, wherein the gas is a gaseous effluent from a reactor used for the purification with hydrogen to hydrocarbons from refinery processes or petrochemical .

12. Measuring method according to one of Claims 7 to 10, used to monitor the progression and / or to ensure that the end of sulfurization step of a hydrotreating catalyst.

13. Installation wherein a gas stream containing hydrogen sulphide is likely to be generated, characterized in that it incorporates a device obtained by mounting the kit defined in any of claims 1 to 6.

14. Use of the kit according to one of claims 1 to 6 for measuring the concentration of hydrogen sulfide from a gas capable of containing said gas comprising at least 50% hydrogen by volume.

15. Use according to claim 14, wherein the gas may contain hydrogen sulphide is gaseous effluent of a reactor used for the purification of hydrocarbons from refining processes or derived from petrochemicals.