GB2470186A

GB2470186A - Safety apparatus for the capture and removal of gases

Info

Publication number: GB2470186A
Application number: GB0908039A
Authority: GB
Inventors: David Foster; Paul Hancock
Original assignee: Sts Resources & Technology Ltd
Current assignee: Sts Resources & Technology Ltd
Priority date: 2009-05-11
Filing date: 2009-05-11
Publication date: 2010-11-17
Anticipated expiration: 2029-05-11
Also published as: GB2470186B; GB0908039D0

Abstract

The present invention relates to an apparatus for enclosing about a gas emanating source, the apparatus comprises an enclosable member adapted to be located about a gas emanating source to provide a gas permeable enclosure, and a gas evacuation device for evacuating gas from the enclosable member and operable to provide a negative pressure within the enclosable member. The present invention also relates to a method for providing a safety enclosure for an installation, the method comprising the steps of providing a gas permeable enclosure about a gas emanating source, evacuating gas from the gas permeable enclosure, creating a negative pressure environment within the gas permeable enclosure such that net gas flow is into the gas permeable enclosure, and maintaining the negative pressure environment within the gas permeable enclosure.

Description

Apparatus and method for the removal of gaseous fluids from hot The present invention relates to a safety apparatus for the capture and removal of gaseous fluids from a target area, in particular but not exclusively for use in the petrochemicals industry, to maintain a safe working environment within an area in which hot work is to take place.

The invention further relates to a method of evacuating noxious and/or volatile gases from an enclosed work area.

The present invention relates to an apparatus for use on an installation, optionally in connection with a conventional habitat, in which work that involves heat production such as flames, sparks and the like, hereinafter referred to as "hot works" is carried out, wherein the habitat is erected to isolate the internal environment from the surroundings, and where an overpressure of air is created in the habitat to prevent ingress of inflammable gases, and comprising systems for supply of electricity to equipment inside the habitat, and also air to establish an overpressure, and an alarm system that can warn or irregularities and the like.

A habitat means the same as a closed chamber, a utility tent, a house or the like where the object can be completely isolated from its surroundings.

As a rule, such habitats are constructed from flame retardant cloth or aluminium or tin plates, adapted for the particular application case. The habitat can have a large number of different shapes, according to the specific objects of the application.

In the following, the term habitat will be used for such closed room/chamber only.

Habitats are used in conditions where it is forbidden to use open fire or carry out work that leads to a danger of fire or explosions, such as heat generation, sparks and the like from welding, grinding, cutting and/or sandblasting. For example, typical tasks when metal parts or pipes are to be welded together.

This is particularly the case for offshore oil-platforms where drilling for hydrocarbons is carried out and/or crude oil is produced. Such installations have as a rule their own separation/zoning system. If unintended heat generation of a given size arises in the relevant area/zone, a risk of explosions can emerge due to ignition of the oil and/or gas.

Therefore, the safety requirements are extra stringent for all such tasks on platforms.

In spite of the stringent safety measures, conventional habitats are still susceptible to gas leaks and the like, emanating from sources within the habitat. Typically it has been up to the operators inside the habitat, or erecting the habitat, to register this themselves and stop the welding process, etc., or to find a way to erect the habitat so as to exclude the gas emanating source for the internal environment of the habitat, so that dangerous situations that can lead to fire or explosions do not arise.

Occasionally, an additional system, which is related to the gas warning itself, is installed, so that the system will give out a warning if gas enters the area. However, one is still forced to rely on manual action by the operator to stop the welding etc, or to erect the habitat correctly to exclude the gas emanating source hazard.

Hot works within certain areas of an installation would otherwise be prohibited under safety regulations, such as ATEX zoning regulations.

The habitat is erected to encase the hot work area and is subsequently filled to overpressure with safe air. The positive pressure within the habitat then allows hot works to be carried out whilst preventing the ingress of unsafe air from the environment in which the hot works are being undertaken.

Exemplary habitats include standard and advanced habitats available from STS Resources and Technology Limited, UK. These habitats provide positive-pressure working environments. Advanced habitats may comprise a full shutdown system (shutting down electrical and pneumatic tools) and an alarm which is triggered in response to detection of gas internal to the habitat, around the perimeter of the habitat, at the air intake fan and/or in case of low pressure (fan failure) or excess heat inside the habitat, for example. This provides an automatic shutdown of the hot works should the operating environment become unsafe.

However, in general, it is a disadvantage with the present habitats that they must be erected around a gas emanating source or otherwise in a way so as to exclude the gas emanating source from the internal environment of the habitat.

It is an object of the present invention, therefore, to provide a new solution which eliminates at least one of the abovementioned problems.

More specifically, it is an aim of the invention to provide a solution that removes more of the risk associated with hot works on offshore or onshore petrochemical installations.

In a first aspect, the present invention provides an apparatus for enclosing about a gas emanating source comprising: an enclosable member adapted to be located about a gas emanating source to provide a gas permeable enclosure; a gas evacuation device for evacuating gas from the gas permeable enclosure, and operable to provide a negative pressure within the gas permeable enclosure.

When referred to herein, the term "negative pressure" shall mean a pressure less than the ambient or the external pressure outside the gas permeable enclosure. In other words, the gas pressure external of the gas permeable enclosure is higher than the gas pressure internal of the gas permeable enclosure.

In embodiments of the invention, when the enclosable member is located about and fixed around the gas emanating source such that a gas permeable enclosure is formed, the net gas flow rate is into the gas permeable enclosure from the atmosphere surrounding the gas permeable enclosure. In this way, noxious and/or volatile gases emanating from a gas emanating source within the gas permeable enclosure will be retained in the enclosure by the pressure gradient across the enclosable member.

In embodiments of the invention, the gas emanating source is a pipestock, valve or the like. It will be understood upon reading the present disclosure that the gas emanating source may be any source from which a gas is seeping or leaking. It will further be understood that, on gas and/or oil installations or the like, a gas leak or seepage is likely to be of noxious and/or volatile gas therefore creating a risk of explosion or inhalation if the gas is not allowed to vent to the atmosphere, for example.

The apparatus of the present invention is, therefore, compatible with known positive pressure enclosures/habitats wherein the positive pressure habitat is created to allow hot works to be carried out in areas/zones on or within the installation which would otherwise be prohibited for safety reasons. If, however, a positive pressure habitat is constructed about a gas emanating source, the risk of explosion due to ignition of the gas or inhalation of the gas by operatives working within the positive pressure habitat is increased as the emanating gas is no longer able to vent to the atmosphere. Therefore, providing the apparatus of the present invention will, once again, create the safety required either within the positive pressure environment or otherwise by confining the emanating gas to the apparatus of the invention and, in certain embodiments, providing means to vent the emanating gas away from the habitat or danger zone.

In embodiments of the present invention, the enclosable member comprises at least one panel of flexible structural material.

Alternatively, or in addition, the enclosable member may comprise at least one panel of flexible fireproof material.

In preferred embodiments of the invention, the enclosable member comprises a plurality of panels of flexible structural material.

More specifically, the gas permeable enclosure may comprise a flexible fireproof material which is configured to be fixed about a gas emanating source by at least one fixing means.

In various embodiments, the fixing means comprises mechanical fixing means. More specifically, the fixing means may comprise one or more of: rivets, nuts, bolts, zips, hooks and eyes, Velcro fasteners, or the like.

In this way, the apparatus may be formed in a modular structure such that a gas permeable enclosure of any shape or size may be formed in situ.

In embodiments of the present invention, the gas evacuation device is a pump.

In preferred embodiments, the gas permeable enclosure comprises a gas evacuation conduit configured to be connected to the gas evacuation device.

In various embodiments the apparatus may further comprise a gas treatment apparatus in fluid communication with the gas evacuation conduit.

In various embodiments the apparatus may further comprise a gas filtration apparatus in fluid communication with the gas evacuation conduit.

The gas filtration apparatus may be a quenching filter which renders the exhaust gases in the atmosphere safe from toxins and/or explosive gases or the like.

In various embodiments the apparatus may further comprise a gas capture apparatus in fluid communication with the gas evacuation conduit.

In various embodiments the apparatus may further comprise a gas vent downstream of and in fluid communication with the gas evacuation conduit. In this way, the gas emanating from the gas emanating source may be streamed to a safe location whence it is vented to the atmosphere without hazard.

In various embodiments the apparatus may further comprise a gas monitoring system. The evacuated gas may be monitored for the presence and levels of various gases of a volatile and/or noxious nature.

For example, those gases may include hydrogen sulphide, carbon monoxide, carbon dioxide, oxygen, sulphur dioxide and many gaseous hydrocarbons. An exemplary safety system is described in US Patent No. US7,397,361.

The gas monitoring system may, in turn, be operably linked to a safety shutdown system which shutdown system will initiate shutdown of the hot work if monitored gas levels rise above a preselected level and/or if the pressure within the gas permeable enclosure rises above a preset level.

Optionally, the shutdown system may further comprise an audible and/or visible alarm should this condition arise.

In this way, the gas pressure within the gas permeable enclosure can be continuously monitored in order to ensure that the exhaust/evacuation systems are operating correctly and efficiently; that the gas filtration apparatus (if present) is not blocked; that the gas evacuation device is running at the prescribed gas evacuation flow rate; and that the gas evacuation device has not been disconnected, for example. Furthermore, the gas monitoring system may be configured to be operable to monitor the gas flow rate from the gas emanating source. Thus, the gas flow rate from the gas emanating source can be monitored to ensure that the gas flow therefrom has not reached such a level that the negative pressure within the gas permeable enclosure is not sufficient to draw gas away from the gas emanating source.

It is envisaged that the gas monitoring system may, in addition, be configured to monitor the gas evacuated from the gas permeable enclosure for gases not expected to be present in the evacuated gas flow.

In various embodiments the apparatus may further comprise a data logging device. The data logging device is preferably operable to record the constituent gases and, optionally, the levels of those constituent gases, in the evacuated gases and/or in the gas permeable enclosure itself.

The data logging device may be operably linked to the gas monitoring system in certain embodiments of the invention.

In this way, the data logging device may continuously record the levels of gas at one or more locations such that a safety officer may study the record to find out what, if anything, has malfunctioned during the hot In embodiments of the apparatus of the invention, a manual shutdown system may be provided. In this way, the system may be shutdown at any time by a manual operation.

In various embodiments the apparatus may further comprise a support means for the gas permeable enclosure.

More specifically the support means may comprise an exoskeleton external of the gas permeable enclosure operable to prevent implosion of the gas permeable enclosure when the gas pressure internal of the enclosure is less than the gas pressure external of the enclosure.

In a second aspect, the present invention provides a method for providing a safety enclosure for an installation, the method comprising the steps of: a. Providing a gas permeable enclosure about a gas emanating source; b. Evacuating gas from the gas permeable enclosure; c. Creating a negative pressure environment within the gas permeable enclosure such that net gas flow is into the gas permeable enclosure; d. Maintaining the negative pressure environment within the gas permeable enclosure.

In embodiments of the second aspect of the invention, the negative gas pressure may be created and maintained by evacuating gas continuously from the gas permeable enclosure.

It will be understood that the some of the features of various embodiments of the first and second aspects of the invention may be equally applicable to other embodiments of the invention.

It will readily be understood that the apparatus of the present invention may be used in conjunction with a habitat suitable for use in environments where there is the possibility of fire and/or explosion wherein that compatible habitat is constructed about an area and is operated at positive pressure relative to the surrounding environment. By providing the apparatus of the present invention, a gas emanating source can be isolated either within a larger habitat or otherwise, such that the larger habitat need not be constructed around the gas emanating source so as to maintain same external the larger habitat whilst ensuring the larger habitat is still safe for the continuance of hot works therewith in.

Furthermore, due to the compact and optionally modular nature of the apparatus of the invention, same provides a readily portable safety equipment which may be easily and swiftly deployed to maintain safe hot It will also be understood that the present invention will have application in offshore and onshore oil and/or gas installations, in refineries for example, within the chemical industry and at other processing and operating plants where tasks such as hot works are to be carried out in the vicinity of gas emanating sources such as leaking pipework, for example, where shutdown or conventional habitats would be difficult or cumbersome to erected and maintain.

In order that the invention be easily understood and readily carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which:-Figure 1 shows a schematic perspective view of a hot work habitat comprising a plurality of connected panels and known in the prior art; Figure 2 is a schematic representation, in plan view, of an apparatus according to an embodiment of the first aspect of the invention; and Figure 3 is a schematic representation, in plan view, of a panel of the embodiment of the apparatus of Figure 2.

Referring to Figure 1, there is shown a habitat known from the prior art and generally indicated by reference numeral 10, comprising a plurality of connected panels 20. The habitat 10 may be assembled around an area in which hot work is to take place. The connected panels 20 are supported by a structural frame 12 and the habitat 10 also includes an access door 14 for accessing the habitat interior.

In use with the habitat 10, the fireproof layer 24 faces inwardly towards the habitat interior to assist in containing any fire which may break out within the habitat 10 during hot working. The flame retardant structural layer 22 faces outwards from the habitat 10 to protect the habitat 10 from heat generated externally of the habitat 10. The composite arrangement of the panel 20 makes the panel 20 better able to withstand activities which might otherwise breach the panel 20, such as being exposed to a sharp edge or a concentrated shower of sparks.

The flame retardant structural layer 22 includes attaching means (not shown) along its edges. The attaching means in the case of the panel 20 is a series of zip fasteners; one half of a first zip fastener being fitted along a first edge of the panel 20, one half of a second zip fastener being fitted along a second edge of panel 20 etc.. Each half zip fastener is adapted to engage with a complementary half zip fastener (not shown) on an adjacent panel.

Also visible in Figure 1 is a protective strip 34. The protective strip 34 is made of flame retardant material and protects the external surface of the zip fastener from heat arising externally of the habitat 10. The protective strip 34 is attached to the panels 20 by hook and loop fastenings (not shown).

The conventional habitat depicted in Figure 1 may include an airlock, preferably a fireproof airlock formed to be securable to the habitat itself.

The habitat may further be provided with a support structure such as scaffolding for supporting the habitat.

The mechanical fastenings depicted in Figure 1 are equally applicable to the embodiments of the present invention depicted in Figures 2 and 3 when the apparatus of the present invention is made up of a plurality of panels which may be fixed to one another to form the enclosable member.

Referring to Figure 2, there is depicted a plan view of an apparatus according to a first embodiment of the invention, generally depicted by the reference numeral 100. The apparatus 100 has a first panel 110 formed of a flexible, fireproof material and a second panel 120 also formed of a flexible, fireproof material. The first and second panels 110, 120 together form an enclosable member which can be located about a gas emanating source to form a gas permeable enclosure. The gas emanating source may be a pipestock, a leaking valve, or the like, on a gas and/or oil installation, for example. The first panel 110 is shaped to be locatable around a pipe or valve for example, which pipe or valve is the gas emanating source. The first panel has a half zip fastener 1 30a and a further half zip fastener 1 30b. Half zip fastener 1 30a, is adapted to engage with complementary half zip fastener 1 30b on the opposing edge of the first panel 110. Thus, the first panel 110 is formed about the gas emanating source. The second panel 120 is fastened to the first panel by way of hooks and eyes 140.

The second panel 120, has eye holes 1 50a and 1 SOb on opposing edges of the panel 120. The panel 120 is formed into the gas permeable enclosure may hooks passing through eyes 150a and 150b thereby drawings the edges of the second panel 120 together.

The enclosable member further has a section 160 through which access to the gas emanating source may be gained through an access opening 170.

Access opening 170 is closable by way of Velcro hooks 161 a and Velcro eyes 161b.

As depicted in Figure 3, second panel 120 may have a panel 180 welded and sewn into the face of the second panel 120. The panel 180 has a conduit passage hole 190 formed therein through which the gas evacuation conduit may be passed. In operation, the gas within the gas permeable enclosure formed by panels 110 and 120 is evacuated through the gas evacuation conduit (not shown) which is in fluid communication with the inside of the gas permeable enclosure through conduit passage hole 190.

In use, the apparatus as depicted in Figures 2 and 3, may be formed about another piece of equipment which is the source of a gas leak or seepage. The enclosure thus formed encases the gas source thereby forming an enclosure from which gas may be evacuated by a gas evacuation device, such as a fan or a pump, for example. The enclosure must be gas permeable so as to allow ingress of surrounding air to establish a gas pressure gradient across the enclosure such that the internal gas pressure is less than the external gas pressure. Thus, surrounding air is forced into the enclosure to facilitate evacuation through the gas evacuation device. In this way, a so-called negative pressure environment is created such that gas leakage from the enclosure is prevented by the gas pressure gradient across the enclosure member forming the gas permeable enclosure.

Various modifications to the apparatus of the invention are envisaged. In particular, first panel 110 and second panel 120 may be formed integrally with one another. Further, the gas permeable enclosure may be of any suitable shape and form although it is much preferred that the apparatus according to the invention is portable and compact to facilitate easy deployment in most industrial settings and installations.

Furthermore, the apparatus 100 may be formed around an internal support structure to prevent the pressure gradient formed across the panel between the external environment and the internal environment within the apparatus 100 forcing the panels to implode.

Claims

Claims 1. Apparatus for enclosing about a gas emanating source comprising: an enclosable member adapted to be located about a gas emanating source to provide a gas permeable enclosure; a gas evacuation device for evacuating gas from the enclosable member, and operable to provide a negative pressure within the enclosable member.
2. An Apparatus according to claim 1, wherein the net gas flow rate is into the gas permeable enclosure from the atmosphere surrounding the gas permeable enclosure.
3. An apparatus according to claim 1 or claim 2, wherein the gas emanating source is a pipestock, valve or the like.
4. An apparatus according to any one of claims 1 to 3, wherein the enclosable member comprises at least one panel of flexible structural material.
5. An apparatus according to any one of claims 1 to 4, wherein the enclosable member comprises at least one panel of flexible fireproof material.
6. An apparatus according to any one of claims 1 to 5, wherein the enclosable member comprises a plurality of panels of flexible structural material.
7. An apparatus according to any one of claims 1 to 6, wherein the gas permeable enclosure comprises a flexible fireproof material which is configured to be fixed about a gas emanating source by at least one fixing means.
8. An apparatus according to claim 7, wherein the fixing means comprises mechanical fixing means.
9. An apparatus according to claim 8, wherein the fixing means comprise one or more of: rivets, nuts, bolts, zips, hooks and eyes, Velcro fasteners, or the like.
10. An apparatus according to any one of claims 1 to 9, wherein the gas evacuation device is a pump.
11. An apparatus according to any one of claims 1 to 10, wherein the gas permeable enclosure comprises a gas evacuation conduit configured to be connected to the gas evacuation device.
12. An apparatus according to any one of claims 1 to 11, further comprising a gas treatment apparatus in fluid communication with the gas evacuation conduit.
13. An apparatus according to any one of claims 1 to 12, further comprising a gas filtration apparatus in fluid communication with the gas evacuation conduit.
14. An apparatus according to any one of claims 1 to 13, further comprising a gas capture apparatus in fluid communication with the gas evacuation conduit.
15. An apparatus according to any one of claims 1 to 14, further comprising a gas vent downstream of and in fluid communication with the gas evacuation conduit.
16. An apparatus according to any one of claims 1 to 15, further comprising a gas monitoring system.
17. An apparatus according to any one of claims 1 to 16, further comprising a support means for the gas permeable enclosure.
18. An apparatus according to claim 17, wherein the support means comprises an exoskeleton external of the gas permeable enclosure operable to prevent implosion of the gas permeable enclosure when the gas pressure internal of the enclosure is less than the gas pressure external of the enclosure.
19. A method for providing a safety enclosure for an installation, the method comprising the steps of: a. Providing a gas permeable enclosure about a gas emanating source; b. Evacuating gas from the gas permeable enclosure; c. Creating a negative pressure environment within the gas permeable enclosure such that net gas flow is into the gas permeable enclosure; d. Maintaining the negative pressure environment within the gas permeable enclosure.
20. A method according to claim 19, wherein the negative gas pressure is created and maintained by evacuating gas continuously from the gas permeable enclosure.