BARRIER ASSEMBLY

Abstract

A barrier assembly used in the protection of personnel at worksites and/or residential areas from escapes of gas. Such a barrier assembly controls the lateral and vertical spread of gas in the event of an escape of the gas, even more particularly toxic gas. The barrier assembly can be used at operating sites where gases are produced, and in particular where high concentrations of toxic gases (e.g. CO2, H2S, SO2, mercaptans etc.) are present. The barrier assembly can, optionally acting as a safety system in the event of an accidental uncontrolled release of these toxic gases into the atmosphere.

Claims

1. A barrier assembly for use in protection of personnel at worksites and/or residential areas from escapes of gas, the barrier assembly comprising a first gas-permeable wall member permitting passage of the gas through the first gas-permeable wall member; an inlet side facing a high concentration of gas; an outlet side; and a space between the inlet and outlet sides of the barrier assembly, wherein the inlet side of the barrier assembly is a gas permeable wall member.

2. The barrier assembly as claimed in claim 1, further comprising a second gas-permeable wall member spaced apart from the first gas-permeable wall member by a space at least partially filled with a material.

3. The barrier assembly as claimed in claim 1, further comprising a frame on which the first gas-permeable wall member is supported, the first gas-permeable wall member being adapted to connect to the frame.

4. The barrier assembly as claimed in claim 1, comprising a base, and wherein the first gas-permeable wall member extends in a direction that is perpendicular with respect to a face of the base.

5. The barrier assembly as claimed in claim 2, wherein the material is a material forcing the gas diffusing through the space to diffuse around the material within the space.

6. The barrier assembly as claimed in claim 5, wherein the material is a particulate material, forming a particulate bed within at least a portion of the space.

7. The barrier assembly as claimed in claim 5, wherein the material comprises a reactive material adapted to react with the gas.

8. The barrier assembly as claimed in claim 5, wherein the material is adapted to adsorb or absorb the gas.

9. The barrier assembly as claimed in claim 5, wherein the material comprises a ceramic material.

10. The barrier assembly as claimed in claim 5, wherein the material comprises a chemically inert matrix incorporating a reactive material adapted to chemically react with the gas within the space.

11. The barrier assembly as claimed in claim 1, further comprising a flow path permitting gas to flow from one side of the barrier assembly to the other.

12. The barrier assembly as claimed in claim 1, wherein the first gas-permeable wall member comprises a mesh.

13. The barrier assembly as claimed in claim 2, wherein the first and second gas-permeable wall members have openings permitting passage of the gas through the first and second gas-permeable wall members, and wherein the first and second gas-permeable wall members are connected on either side of the barrier assembly, with the wall members spaced apart from one another, creating a space within the barrier assembly between opposing inner faces of the first and second gas-permeable wall members.

14. The barrier assembly as claimed in claim 13, wherein the wall members comprise a mesh, and wherein the material comprises a chemically inert matrix incorporating a reactive material adapted to chemically react with the gas within the space.

15. A method of confining a gas leak to protect personnel at worksites and/or residential areas from escapes of gas, using a barrier assembly comprising a gas-permeable wall member having openings therein adapted to permit passage of gas through the gas-permeable wall member, the method comprising: arranging the barrier assembly in proximity to a gas leak; and diffusing the gas through openings in at least a portion of the gas-permeable wall member.

16. The method as claimed in claim 15, the method further comprising: combatting lateral and vertical spread of leaked gas by diffusing the gas through the barrier.

17. The method as claimed in claim 15, the method further comprising: arranging the barrier between a work site for personnel and the gas leak.

18. The method as claimed in claim 15, wherein the barrier assembly further comprises another gas-permeable wall member connected to the gas-permeable wall member on opposite sides of a frame, wherein the gas-permeable wall member and the another gas permeable wall member are spaced apart by a space within the barrier assembly between opposing inner faces of the gas-permeable wall member and the another gas permeable wall member on opposite sides of the frame, and wherein the method further comprises: diffusing the gas into the space within the barrier assembly.

19. The method as claimed in claim 18, wherein the space formed between the wall members is at least partially filled with a material, and wherein the method further comprises: forcing the gas diffusing through the space to diffuse around the material within the space.

20. The method as claimed in claim 19, wherein the material comprises a reactive material adapted to react with the gas, and wherein the method includes reacting the reactive material with the gas to combat toxicity and/or corrosive nature of the gas.

21. The method as claimed in claim 19, wherein the method includes retaining at least some of the gas within the space by adsorbing at least some of the gas onto the material within the space.

22. The method as claimed in claim 19, wherein the method includes treating the material within the space with a liquid comprising a composition adapted to react with the gas and to combat its toxicity or corrosive nature, before passing the gas through the barrier assembly.

23. The method as claimed in claim 15, further comprising flowing gas from one side of the barrier assembly to the other.

24. The method as claimed in claim 15, wherein the barrier comprises first and second barrier assemblies, wherein the first barrier assembly is closer to the gas leak than the second barrier assembly, wherein the first barrier assembly incorporates a reactive composition within a space, and wherein the second barrier assembly does not include a reactive composition within the space.

25. The method as claimed in claim 15, wherein the barrier assembly is the barrier assembly according to claim 1.

26. A barrier assembly according to claim 1, wherein the first gas-permeable wall member is a panel that is connectable to a frame and comprise a plurality of gas-permeable openings apt to reduce lateral and vertical spread of gas.

27. A safety system comprising a first and a second barrier assemblies as defined in claim 1, wherein the first barrier assembly incorporates a reactive composition within the space, and the second barrier assembly including or not including a reactive composition within the space, preferably including a reactive composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Examples of the present disclosure are shown, by way of example only, in the accompanying drawings, in which:

[0050] FIG. 1 shows a perspective side view of a partially assembled barrier assembly according to a first example;

[0051] FIG. 2 shows a front view of FIG. 1 assembly;

[0052] FIG. 3 shows a plan section view through the FIG. 1 assembly;

[0053] FIG. 4 shows a side section view through an alternative example of the FIG. 1 assembly;

[0054] FIG. 5 shows a detailed view of a portion of the FIG. 3 view; and

[0055] FIG. 6 shows a perspective side view of a partially assembled barrier assembly according to a second example.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0056] Referring now to the figures, a first example of a barrier assembly 10 is shown in FIG. 1. The barrier assembly 10 comprises a frame 30 comprising vertical and horizontal frame members 31, 32 arranged to form substantially contiguous rectangular apertures, and in this example the frame 30 is generally planar. This results in a generally planar barrier assembly 10, but in some examples, the frame 30 need not be planar, and could have an arcuate structure, enabling a barrier that had a curved or arcuate appearance.

[0057] The frame members 31, 32 are secured together by suitable fastenings, for example bolts, and are mounted on a base 20, which is normally deployed on ground adjacent to a well or other structure from which leaking gas is to be contained.

[0058] The base 20 generally comprises a rectangular plinth, which can be formed from concrete or any suitable material, and is typically sufficient to provide ballast to assist with stability of the barrier assembly 10 when constructed. The base 20 is optionally deployed parallel to the ground, and typically resting upon it, and the frame 30 optionally extends perpendicularly with respect to a plane of the base 20, optionally extending vertically from the flat lower horizontal face of the base 20, although in some examples, the frame can extend at other angles.

[0059] The frame 30 has an inlet side (facing a high concentration of gas) and an outlet side (where the concentration of outlet gas is lower than on the inlet side), and in this example, each side of the frame 30 has a perforated plate 40 attached to the frame and supported by it. Optionally the plates 40 are secured to the frame 30 by fixings such as bolts etc. In this example, as best shown in FIG. 3, each side of the barrier assembly 10 has a perforated plate 40 with openings in the form of perforations 41 extending through the plate, thereby allowing gas passage from one side of the plate 40 to the other. The perforations are arranged in a regular repeating pattern across the plates 40. As best shown in FIG. 3, the plates 40 in this example are generally parallel to one another in the barrier assembly 10, and are spaced apart from one another by the width of the frame members 31, 32, leaving a gap 50 between the inner opposing surfaces of the plates 40.

[0060] As can be seen best in FIG. 3, this arrangement permits passage of gas through the plates 40 via the perforations 41 from the outside face of one plate (on the inlet side of the barrier assembly) through the inner space 50 between the plates 40, and through the plate 40 on the opposite side, so that gas can flow from the inlet side of the barrier assembly 10 to the outlet side.

[0061] In this example, the space 50 between the plates 40 is optionally filled with a matrix material 50m, which in this case comprises a plurality of tubular rings, which have a generally cylindrical wall, surrounding an internal bore that is open at each end. In this case, the rings are Raschig rings 51, which can optionally be formed from a porous ceramic material, which can optionally be particularly adapted to adsorb active or harmful components of the gas. The rings 51 increase the surface area available for absorption of the gas onto the rings 51 within the space 50 as the gas passes through the perforations 41 in the plates 40, and diffuses through the internal space 50 within the barrier assembly 10. Other forms of particulate matrix material can be used within the internal space 50.

[0062] As best shown in FIG. 4, in one alternative example, only a lower part of the plates 40a are provided with openings or perforations 41a, allowing passage of the gas through only a portion of the barrier assembly, and optionally in that arrangement, only the perforated portion of the space 50a is between the plates 40a is filled with the matrix 50m.

[0063] Optionally, the internal diameter of the Raschig rings is 5 to 10 mm, and the axial length of each ring is approximately 20 to 30 mm, although this can be varied in different examples, to provide different surface area ratios.

[0064] The openings or perforations 41 are sufficiently small as to contain the rings 51 within the internal space 50 within the barrier 10. Optionally, the rings 51 are simply filled into the internal space 50, without any sorting or alignment of the rings, so the various pathways through the internal space 50 between and through the rings 51 are essentially random, forcing the gas passing through the barrier assembly 10 to follow a path through the barrier assembly which is optionally labyrinthine, and which flows the gas through the matrix of the rushing rings 51 in an optionally random manner, permitting increased absorption of the gas onto the large surface area provided by the matrix, and increased diffusion of the gas in a lateral direction through the matrix material 50m.

[0065] Referring now to FIG. 6, a second example of a barrier assembly 110 is described, having a frame 130, mounted on a base 120 essentially as described for the first example, and having a matrix 150m contained within an internal space 150 between the two sides of the barrier 110. In this example, the matrix 150m also comprises a plurality of Raschig rings 151, which are optionally in a random arrangement as previously described.

[0066] The FIG. 6 example differs from the FIG. 1 example in that the perforated plates 40 in the first example are replaced by mesh screens 140 having mutually perpendicular warp and weft strands which are sufficiently tightly meshed to contain the Raschig rings 151 within the internal space 150 between the two faces of the barrier assembly 110, but which have openings which do not offer any practical barrier to the flow of gas through the barrier assembly 110, and allow practically free flow of gas through the screens 140, via gas-permeable openings 141 as best seen in the detailed view to the left of FIG. 6.

[0067] As described for the previous example, gas can pass freely through the screens 140 from one side of the barrier assembly 110 to the other, passing through the matrix 150m contained within the internal space 150.

[0068] In the FIG. 6 example, the Raschig rings 151 are optionally coated with a reactive material which in this example comprises a ferric hydride oxide, which is at least partially adsorbed onto the Raschig rings 151. In this example, the Raschig rings 151 are optionally porous, and at least some of the ferric hydride oxide is adsorbed onto them. In certain examples, the rings 151 can be treated with a liquid containing the reactive composition, which soaks into the porous rings 151 and is retained within the pores and on the surfaces of the rings, so that when the gas is adsorbed onto the rings 151, it reacts with the reactive composition to deactivate or otherwise combat the toxic and/or corrosive nature of the gas. Thus the toxic or corrosive nature of the gas is ameliorated within the space inside the barrier assembly, and any gas escaping from the outlet side of the wall members is less toxic and/or less corrosive as well as being less concentrated.

[0069] Upon passage of hydrogen sulphide through the barrier assembly, the hydrogen sulphide gas passes freely through the outer screens 140, and diffuses through a labyrinthine pathway within internal matrix 150m contained within the internal space 150 within the barrier assembly 110, and reacts with the ferric hydride oxide adsorbed onto the Raschig rings 151 dispersed within the matrix 150m. The reactive ferric hydride oxide reacts with the hydrogen sulphide to attenuate the toxicity and optionally the corrosive nature of the hydrogen sulphide. The diffusion of the gas within the matrix retains at least some of the gas within the space, and when it flows out of the barrier assembly on the outlet side of the barrier, its concentration is lower than at the inlet side, and is optionally below concentrations that adversely affect health or personnel or integrity of infrastructure.

[0070] Optionally, the matrix contained within the internal space of the barrier assembly 110 can be provided with a coating or treatment which increases its capacity for adsorption of the gas when passing through the matrix, without necessarily reacting chemically with the gas.

[0071] In use, the barrier assembly is constructed a suitable distance from the locus of a gas leak or possible future gas leak, for example, at the wellhead of an oil or gas well during the drilling phase, between the wellhead and a work site occupied by personnel, who would be at risk of exposure to uncontrolled escape of well gasses such as hydrogen sulphide. The barrier assembly is constructed of as many modular panels of base/frame/wall member as is required to shield the work site from the wellhead, for example, 2, 3, 4, 5 or more panels as shown in FIG. 1, and these are typically connected side-by-side to form a barrier between the worksite and the wellhead, so that gas escaping from the wellhead during drilling operations must diffuse through, over and around the barrier assembly before reaching the worksite. Upon the release of gas from the wellhead, the gas diffuses through the openings on an inlet side of the barrier assembly. The inlet side of the barrier generally has a high concentration of gas which could pose a risk to health of workers at the inlet side, or damage to plant and machinery at the inlet side. The gas flows through the perforated wall members at the inlet side and into the space between the wall members on opposite sides of the frame, but is at least partially retained in the space. Thus the gas diffusing out of the perforations on the outlet side is at a lower concentration than the gas at the inlet side, and is less likely to harm personnel or adversely affect the integrity of plant and equipment at the outlet side of the barrier assembly.

Example 1

[0072] The apparatus of FIGS. 1-5 was used in a test as follows: A source of H.sub.2S gas was allowed to escape from a gas source upstream of the barrier assembly of FIGS. 1-5. A hypothetical target located 200 m downstream of the gas source and on the other (downstream) side of the barrier assembly comprised a sensor capable of detecting the gas concentration at a height of 1.7 m. The sensor measured the gas concentration at the downstream location. The criterion for the test was that at least the concentration threshold of H.sub.2S of 600 ppm should be reached within 75 seconds of initiation of gas release. The 75 s time limit corresponds to an estimated time required to put on a mask. The barrier assembly, 5 m high and 20 m wide, comprised a perforated vertical wall having an empty space fraction of 25% obtained with ¼″ holes spaced at approximately W. The target located 200 m from the release source was affected by a concentration of approximately 200 ppm after 75 s. It is confirmed the efficacy of the wall concept and the potentialities of a perforated wall according to the present disclosure.

Example 2: Test with a Perforated Wall Containing a H.SUB.2.S Scavenger

[0073] A barrier assembly according to FIG. 6, 10 m high, 0.25 m deep and 150 m long was considered as the basis for this example. The wall surfaces comprised, on each side, a square metal mesh of side 10 mm. The wall was randomly filled up of Raschig rings of size 25 mm comprising ferric nitrate as a scavenger.

[0074] The Raschig rings were prepared as follows: 100 kg of Grace commercial silica gel, Grace XWP silica gel grade 250 MP, surface area 175 m.sup.2/g, pore volume 1.2 ml/g, were treated with an aqueous solution prepared with 50 liters of distilled water in which 40 kg of ferric nitrate [Fe(NO.sub.3).sub.3.9H.sub.2O] were dissolved. The solid so obtained was dried at 100° C. overnight and then calcined at 550° C. for 6 hours, supplying a flow of air saturated with water vapour. In this way a scavenger material comprising ferric oxide hydrate dispersed on silica was obtained. The silica material incorporating the scavenger agent was then used to form Raschig rings by mixing it with 10% by weight of alumina as a binder and 5% by weight water acidified with 1% of acetic acid to form a paste (all percentage referred to the weight of silica material), and extruding and cutting it through a suitable die to obtain Raschig rings of size 25 mm.

[0075] The flow characteristics for the rings are: characteristic diameter D.sub.c=9.2 mm and porosity ε=0.7. Ergun's equation is assumed to be valid for calculation of pressure losses across the bed:

[00001]$\frac{.Math.\Delta p.Math.}{t}=\frac{150\mu }{D_c^2}\frac{{\left(1-\mathrm{.Math.}\right)}^2}{{\mathrm{.Math.}}^3}v+\frac{1.75\rho }{D_c}\frac{\left(1-\mathrm{.Math.}\right)}{{\mathrm{.Math.}}^3}{v}^2$

where: [0076] t is the thickness of the wall, [0077] p is the dynamic viscosity of the fluid, [0078] p is the density of the fluid, [0079] v is the traverse velocity.

[0080] The wall was affected by:

1. A flow of air due to the presence of wind having a speed of 5 m/s 10 m above the ground and stability class D;
2. A jet of gas caused by the failure of a pressure vessel. It was assumed that the gas present in the jet after bursting had a velocity equal to the speed of sound in a circular cross-section of diameter such as to contain the entire flow emerging from the burst at atmospheric pressure. In this example it was assumed that this circular cross-section was located at a distance of 25 m from the wall and that the axis of the jet was perpendicular to the wall, at a distance of 2 m above the ground. The mean density and the temperature of the emitted gas was also set, together with the concentration of toxic gas (H.sub.2S) at 3%.

[0081] The field of motion in this application can be assessed through digital solution of the Navier-Stokes equations and mass and thermal energy conservation performed using commercial software such as for example STAR-CCM+. The environmental conditions used for the computational wind tunnel were as follows: [0082] released flow of gas 50 kg/s, at an overall temperature of 44° C.; [0083] lower surface represented diagrammatically as an adiabatic wall having a roughness of 3 cm; [0084] inlet cross-section to the calculation domain (downstream of the jet), lateral surfaces and upper surfaces having velocity and turbulence profiles set in relation to the quota according to the Panofsky-Dutton method and ambient temperature of 15° C.; [0085] outlet surface area from the calculation domain at the set atmospheric pressure and ambient temperature.

[0086] The result obtained was that immediately downstream from the wall the H.sub.2S concentration in the jet fell to 1800 ppm and that 38% of the H.sub.2S flow affecting the wall passed through it.

[0087] Assuming a target located at a distance of 200 m from the release and a height above the ground of 1.7 m, the concentration recorded at the target 75 s after release was 64 ppm of H.sub.2S.

Example 3 (Passive Wall)

[0088] It is considered a vertical perforated barrier located at 15 m from the release of gas. Void fraction is 25% and holes size ¼″. The dimensions of the wall (i.e. barrier) are the same as the barrier of example 1.

[0089] It is considered the horizontal release of gas, the release size is 50 mm (hole size) and the position of the hole is @ 1 m above ground.

[0090] A gas flow (release pressure 150 barg, temperature 80° C.) with the following composition: methane as main component (97% mol) and H.sub.2S concentration at 3% mol/mol is directed toward the wall.

[0091] On the other side of the wall (outlet) the gas stream is calculated, by means of fluidodinamics simulations (using the same method as described in example 2), at 5 meters before the barrier, 150 meters after the barrier and 200 meters after the barrier.

TABLE-US-00001 5 meters 150 meters 200 meters before after after the barrier the barrier the barrier ppm H.sub.2S Perforated barrier 4745 98 67 (Void fraction 25%. Holes size ¼″)

Comparative Example 4 (Passive Wall)

[0092] It is considered a full vertical barrier (non-permeable to gas) having the same dimensions as the wall (i.e. barrier) of example 1, and located at 15 m from the release.

[0093] It is considered the horizontal release, the release size is 50 mm (hole size) and the position of the hole is @ 1 m above ground.

[0094] A Gas flow (release pressure 150 barg, temperature 80° C.) with the following composition: methane as main component (97% mol) and H.sub.2S concentration at 3% mol/mol is directed toward the wall.

[0095] On the other side of the wall (outlet) the gas stream is calculated, by means of fluidodinamics simulations (using the same method as described in example 2), at 5 meters before the barrier, 150 meters after the barrier and 200 meters after the barrier.

TABLE-US-00002 5 meters 150 meters 200 meters before after after the barrier the barrier the barrier ppm H2S Vertical barrier 4745 186 154

[0096] The comparison of the data of example 3 and comparative example 4 shows that at the same distance after barrier, the concentration of H.sub.2S is lower for the barrier according to the present disclosure.

[0097] The following examples 5 to 10 are directed to illustrate the barrier behaviour of reactive filling materials, depending on the thickness of the barrier.

Example 5 (Reactive Wall)

[0098] It is considered a porous barrier, filled with commercial scavenger R7J (i.e. a H.sub.2S scavenger) produced by Sulfatrap®, whose composition is reported below in table 1, whose diameter is 70-100 mesh, the thickness of the scavenger filling is 16 cm.

[0099] A gas flow (gas flow rate: 0.25 m s.sup.−1, temperature: 25° C.) with the following composition: 14,99% H.sub.2S and 85.01% N.sub.2, is directed toward the wall.

[0100] On the other side of the wall (outlet) the gas stream is detected after 1 minute and analyzed with a gas chromatograph.

[0101] The gas flow composition on the other side of the wall (outlet composition) shows a sharp decrease of H.sub.2S (H.sub.2S content: 33 ppm, N.sub.2: one hundred complement).

[0102] Therefore, there is a sharp reduction of the toxicity for a person present on the other side (outlet) of the wall.

TABLE-US-00003 TABLE 2 Chemical composition of the commerical sorbents and their Sulphur Absorbent Capacity Activated Aluminium Aluminio Copper II Copper Iron III Charcoal Oxide Silicate Hydroxide Oxide Oxide CAS# 7440-44-0 CAS# 1344-28-1 CAS# 1318-02-1 CAS# 20427-59-2 CAS# 1317-38-0 CAS#1309-37-1 Scavenger C Al.sub.2O.sub.3 Al.sub.2SiO.sub.5 Cu(OH)2 CuO Fe.sub.2O.sub.3 SulfaTrap [Code] [% w/w] R7J <10 >60 Manganese Manganese Potassium Potassium Propretary Sulfur Carbonate Dioxide Hydroxide Nitrate Material absorption CAS# 20344-49-4 CAS# 598-62-9 CAS# 1313-13-9 CAS# 1310-58-3 CAS# 7757-79-1 capacity Scavenger MnCO.sub.3 MnO.sub.2 KOH KNO.sub.3 ND SulfaTrap [Code] [% w/w] R7J  <2 24

Example 6 (Reactive Wall)

[0103] It is considered a porous barrier, filled with commercial scavenger R7J produced by Sulfatrap®, whose composition is reported in the above table 1, whose diameter is 70-100 mesh, the thickness of the scavenger filling is 3.0 cm.

[0104] A gas flow (gas flow rate: 0.025 m s.sup.−1, temperature: 25° C.) with the following composition: 3,01% H.sub.2S and 96,99% N.sub.2 is directed toward the wall.

[0105] On the other side of the wall (outlet) the gas stream is detected after 6 minute and analyzed with a gas chromatograph.

[0106] The gas flow composition on the other side of the wall (outlet composition) shows a sharp decrease of H.sub.2S (H.sub.2S content: 68 ppm, N.sub.2 one hundred complement).

[0107] Therefore, there is a sharp reduction of the toxicity for a person present on the other side (outlet) of the reactive wall.

Example 7 (Reactive Wall)

[0108] It is considered a porous barrier, filled with commercial scavenger R7J produced by Sulfatrap®, whose composition is reported in the above table 1, whose diameter is 70-100 mesh, the thickness of the scavenger filling is 3 cm.

[0109] A gas flow (gas flow rate: 0.025 m s.sup.−1, temperature: 25° C.) with the following composition: 3,01% H.sub.2S and 96,99% N.sub.2 is directed toward the wall.

[0110] On the other side of the wall (outlet) the gas stream is detected after 6 minute and analyzed with a gas chromatograph.

[0111] The gas flow composition on the other side of the wall (outlet composition) shows a sharp decrease of H.sub.2S (H.sub.2S content: 2025 ppm; N.sub.2: one hundred percent complement).

[0112] Therefore, there is a sharp reduction of the toxicity for a person present on the other side (outlet) of the wall (barrier).

Example 8 (Reactive Wall)

[0113] It is considered a porous barrier, filled with commercial scavenger R7J produced by Sulfatrap®, whose composition is reported in table 1 above, whose diameter is 300-900 μm, the thickness of the scavenger filling is 1 cm.

[0114] A gas flow (GHSV 4000 min.sup.−1, temperature 30° C.) with the following composition: 432 ppm H.sub.2S and N.sub.2 one hundred percent complement, is directed toward the wall.

[0115] On the other side of the wall (outlet) the gas stream is detected after 2 minute and analyzed with a gas chromatograph.

[0116] The gas flow composition on the other side of the wall (outlet composition) shows a sharp decrease of H.sub.2S (H.sub.2S content: 3.82 ppm; N.sub.2 one hundred complement).

[0117] Therefore, there is a sharp reduction of the toxicity for a person present on the other side (outlet) of the wall.

Example 9 (Reactive Wall)

[0118] It is considered a porous barrier, filled with commercial scavenger R7J produced by Sulfatrap®, whose composition is reported in the above table 1, whose diameter is 300-900 μm, the thickness of the scavenger filling is 1 cm.

[0119] A gas flow (GHSV: 4000 min.sup.−1, temperature: 30° C.) with the following composition: 300 ppm H.sub.2S and N.sub.2 one hundred percent complement, is directed toward the wall.

[0120] On the other side of the wall (outlet) the gas stream is detected after 2 minute and analyzed with a gas chromatograph.

[0121] The gas flow composition on the other side of the wall (outlet composition) show a sharp decrease of H.sub.2S (H.sub.2S content: 0.2 ppm, N.sub.2 one hundred complement).

[0122] Therefore, there is a sharp reduction of the toxicity for a person present on the other side (outlet) of the wall.

Example 10 (Reactive Wall)

[0123] It is considered a porous barrier, filled with commercial scavenger R7J produced by Sulfatrap®, whose composition is reported in table 1 above, whose diameter is 300-900 μm, the thickness of the scavenger filling is 1 cm.

[0124] A gas flow (GHSV: 4000 min.sup.−1, temperature: 30° C.) with the following composition: 200 ppm H.sub.2S and N.sub.2 one hundred percent complement, is directed toward the wall.

[0125] On the other side of the wall (outlet) the gas stream is detected after 2 minute and analyzed with a gas chromatograph.

[0126] The gas flow composition on the other side of the wall (outlet composition) show a sharp decrease of H.sub.2S (H.sub.2S content 0.12 ppm; N.sub.2 one hundred complement).

[0127] Therefore, there is a sharp reduction of the toxicity for a person present on the other side (outlet) of the wall.