Portable device for the in-line measurement of the hydrogen sulfide concentration of an off-gas

1. A kit for measuring a hydrogen sulfide concentration of a gas having a hydrogen sulfide concentration and wherein the gas comprises at least 50% hydrogen by volume, wherein the kit comprises separate modules that can be connected to one another to provide a detachable device, the modules comprising:

a measurement module A comprising a measurement chamber M wherein an absorption of a monochromatic electromagnetic radiation by the gas is measured and an absorption measurement related to the hydrogen sulfide concentration is produced, and wherein the measurement chamber M comprises a generally tubular stainless steel vessel having a length of between 5 cm and 80 cm, and wherein the measurement module A has a range of working pressure values, and wherein the measurement module A is contained in a metal housing that is constructed and arranged to be explosion-proof in accordance with European 94/9/EC directive ATEX classification points p and/or e and/or d without the need for an inerting gas;

an expansion module B that brings the pressure of the gas to the range of working pressure values of the measurement module A, wherein the expansion module B comprises an inlet duct that receives the gas having a hydrogen sulfide concentration and an outlet duct, and wherein the outlet duct of expansion module B is configured to connect to an inlet duct of the measurement module A;

a pressure-regulating module C that maintains the pressure of the gas in the measurement chamber M at a pressure lying within the range of working pressure values of the measurement module A, wherein the pressure-regulating module C comprises an inlet duct that is configured to mechanically connect to an outlet duct of the measurement module A and the pressure-regulating module C is further configured to connect to a discharge duct that discharges the gas having a hydrogen sulfide concentration out of the detachable device;

a processing module D that processes the absorption measurement, whereby the concentration of hydrogen sulfide in the gas is determined, wherein the measurement module A is configured to be electrically connected to the processing module D, and wherein the processing module D is contained in a metal housing that is constructed and arranged to be explosion-proof in accordance with European 94/9/EC directive ATEX classification points p and/or e and/or d without the need for an inerting gas.

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

3. The kit according to claim 1 , wherein the electromagnetic radiation is a monochromatic radiation lying in the ultraviolet or visible wavelength range wherein the wavelength of the radiation is between 100 nm and 780 nm.

4. The kit according to claim 1 , wherein the expansion module B brings the pressure of the gas having a hydrogen sulfide concentration to between 500 hPa (0.5 bar) relative and 2000 hPa (2 bar) relative.

5. The kit according to claim 1 , wherein:

the measurement module A has a weight of less than or equal to 60 kg;

the expansion module B has a weight of less than or equal to 20 kg;

the regulating module C has a weight of less than or equal to 20 kg; and

the processing module D has a weight of less than or equal to 50 kg.

6. A method for the continuous measurement of a hydrogen sulfide concentration of an off-gas, wherein the method comprises using a detachable device capable of being connected temporarily to a plant producing said off-gas, wherein the detachable device measures an absorption of a monochromatic electromagnetic radiation by the off-gas and wherein the off-gas comprises at least 50% hydrogen by volume and wherein the detachable device is constructed and arranged to be explosion-proof in accordance with European 94/9/EC directive ATEX classification points p and/or e and/or d without the need for an inerting gas.

7. The method according to claim 6 , wherein the monochromatic electromagnetic radiation is a fixed wavelength infrared radiation emitted by a laser, wherein the wavelength is between 780 nm and 3000 nm.

8. The method according to claim 6 , wherein the monochromatic electromagnetic radiation lies in the ultraviolet or visible wavelength range, wherein the wavelength of the radiation is between 100 nm and 780 nm.

9. A method for the continuous measurement of the hydrogen sulfide concentration of a gas having a hydrogen sulfide concentration, wherein the method comprises using the detachable device provided by the kit according to claim 1 to measure the hydrogen sulfide concentration.

10. The method according to claim 6 , wherein the gas having a hydrogen sulfide concentration is an off-gas from a reactor used for the purification, with hydrogen, of hydrocarbons resulting from refining processes or from petrochemistry.

11. The method according to claim 6 , wherein the method is used for monitoring progression of or for ensuring the end of a process of sulfiding a hydrotreating catalyst.

12. A plant having a gas stream having a hydrogen sulfide concentration wherein the plant integrates the kit according to claim 1 .

13. A method of using the detachable device provided by the kit according to claim 1 for measuring the hydrogen sulfide concentration of a gas having a hydrogen sulfide concentration, wherein the method comprises the steps of:

a) temporarily attaching the detachable device to a plant that produces the gas having a hydrogen sulfide concentration,

b) measuring the hydrogen sulfide concentration,

c) detaching the detachable device from the plant.

14. The method according to claim 13 , wherein the plant comprises a reactor used for purification of hydrocarbons resulting from refining processes or from petrochemistry and the gas having a hydrogen sulfide concentration is an off-gas of the reactor used for purification of hydrocarbons resulting from refining processes or from petrochemistry.