Patent Grant
12007132
The present disclosure relates to systems and methods in the onshore and marine (offshore) processing fields. In particularly, the present disclosure relates to systems and methods useful for manually or automatically shutting down welding, blasting (for example, sand blasting or blasting using any grit), cutting, and any other automated work in liquefied natural gas (LNG) facilities, crude oil refineries, and petrochemical plants, or more generally in any facility where such work needs to be done safely, either while such facilities are in operation, or during facility shutdowns, turnarounds, and the like.
Work may need to be performed in liquefied natural gas (LNG) facilities, crude oil refineries, and petrochemical plants in areas or environments where hydrocarbons or other explosive, flammable, or poisonous gases or vapors may be present. Three components are required for a fire or explosion: oxygen, fuel, heat. If the fuel is gaseous or vaporous, the lower explosive limit (LEL) and upper explosive limit (UEL) are key parameters, for if the gas or vapor is present in concentration between the LEL and UEL, if sufficient oxygen is present, all that is required is a spark, flame, or high heat to cause a fire or explosion. The LEL and UEL of gases and gas mixtures varies. Hydrogen has one of the largest ranges of concentrations between LEL and UEL, sometimes referred to as “explosive range” or flammable range, at 4.0 to 75.0. Methane has a range of 5.0 to 15; hydrogen sulfide has a range of from 4.0 to 44.0.
LNG facilities, crude oil refineries, and petrochemical plants of course may need maintenance either while shutdown or while in operation, the latter sometimes referred to as “on-line.” In either case, work may need to be performed where there is a chance that an explosive, flammable, and/or poisonous gas or vapor could infiltrate the work site during the course of the work, and such environments are deemed “live environments” herein. The current means of performing this work is to construct a habitat or enclosure where workers can work, or simply do the work without any enclosure but wearing Personal Gas Monitors (PGM). Such habitats may employ shutdown systems for sensing when pressure inside the habitat drops below pressure exterior of the habitat. Such habitats and shutdown systems are designed for positive pressure (above atmospheric pressure) inside the habitat, and may automatically shutdown operations upon negative pressure being sensed inside the habitat.
As may be seen, current practice may not be adequate for all circumstances, and at worst may result in injury to workers. There remains a need for more safe, robust safety shutdown systems and methods allowing hot work to proceed during normal operation of facilities, particularly for facilities that may experience both positive and negative pressure in different work areas at the same time during normal operation, or only negative pressure. The systems and methods of the present disclosure are directed to these needs.
In accordance with the present disclosure, safety shutdown systems and methods are described which reduce or overcome many of the faults of previously known systems and methods.
A first aspect of the disclosure is a method of maintaining an atmosphere inside a habitat enclosing a work station and shutting down one, more than one, or all operational equipment inside and/or outside the habitat (for example as dictated by the client, law, or regulation), in certain embodiments at least operational equipment inside and/or outside the habitat, upon the occurrence of an adverse event, the method comprising:
In certain embodiments methods of this disclosure may comprise shutting down operational equipment outside the habitat upon the occurrence of the adverse event, in addition to that inside the habitat. As used herein, the term “operational equipment” means equipment defined by the operator or owner of the facility being worked on as being required to be shut down on the occurrence of an adverse event. “Adverse event” means the presence of explosive, flammable, and/or poisonous gas or vapor inside (alternatively, in certain embodiments outside, or in certain embodiments both inside and outside) the habitat above a maximum set point concentration (which may be independently set for each gas or vapor), or the presence of pressure inside the habitat above a maximum set point pressure, where the set point pressure is below atmospheric pressure, or both of these conditions happening simultaneously or substantially simultaneously (within 30 seconds, or within 20 seconds, or within 10 seconds, or within 5 second, or within 2 seconds, or within 1 second, or less as further described herein). In certain embodiments, temperature (T) may be sensed inside the habitat(s) while pressure (P) and/or humidity (H) are sensed outside the habitat(s). Different habitats within a set of habitats may have different sensor strategies, for example, a sensor for one habitat sensing H inside the habitat, another sensing H outside a second habitat. All combinations of sensing T, P, and/or H inside and/or outside one or more habitats are disclosed herein and considered within the present disclosure. As used herein, “outside” a habitat means an area or region external of the habitat where it is likely or possible that one or more explosive, flammable, and/or poisonous gases may have a reasonable chance of entering the habitat during a job. For example, the outside region may reasonably extend 30 ft. (9 meters), or 40 ft. (12 m), or 50 ft. (15 m) away from the habitat, but an outside region extending 3,000 ft. (900 m) would not be reasonable.
In certain embodiments the method may operate in modes selected from the group consisting of automatic continuous mode, automatic periodic mode, and manual mode. In certain embodiments the one or more operational equipment may be selected from the group consisting of pneumatic, electric, fuel, hydraulic, and combinations thereof. In certain embodiments the one or more explosive, flammable, and/or poisonous gases and vapors may be selected from organic gases and vapors, combinations thereof (for example, an adduct), and mixtures thereof. In certain embodiments the one or more explosive dusts may be inorganic dusts. In certain embodiments the one or more inorganic explosive dusts may be one or more thermal spray metal dusts. In certain embodiments the one or more thermal spray metal dusts may be selected from the group consisting of thermal spray aluminum dust, thermal spray zinc dust, thermal spray copper dust, thermal spray stainless steel dust, thermal spray metal alloy dust, and combinations and mixtures thereof.
In certain embodiments the sensing concentration of the one or more explosive, flammable, and/or poisonous gases or vapors inside and/or outside of the habitat may comprise sensing concentration of explosive, flammable, and/or poisonous gases and vapors selected from the group consisting of natural gas, methane, ethane, ethylene oxide, hydrogen sulfide, oxygen, nitrogen, argon, hydrogen, carbon dioxide, carbon monoxide, propane, butane, pentane, and combinations and mixtures thereof. In certain embodiments the method may comprise sensing concentration of the one or more explosive, flammable, and/or poisonous gases or vapors outside the habitat in addition to inside. In certain embodiments the method may comprise sensing concentration of the one or more explosive, flammable, and/or poisonous gases or vapors at an air intake to the habitat. In certain embodiments the method may comprise wherein the sensing of concentration of the one or more explosive, flammable, and/or poisonous gases or vapors inside the habitat occurs at designated locations inside the habitat, for example, but not limited to the air entrance from an HVAC unit, above a door, near a bottom of a door, adjacent a window.
In certain embodiments the method may comprise operating and/or viewing the logic device from a human/machine interface wired or wirelessly connected to the logic device. In certain embodiments the method may comprise the logic device initiating one or more audio/visual warnings upon the occurrence of the pressure rise in the sensed pressure above the set point pressure, or the rise in concentration of one or more of the one or more sensed concentrations above one or more set point concentrations.
In certain embodiments the method may comprise opening one or more one-way back flash valves in ducts fluidly connecting the EGES with the habitat.
In certain embodiments the method may comprise maintaining an atmosphere inside the habitat, the habitat enclosing a work station for an on-line process, and shutting down operational equipment inside and outside the habitat upon the occurrence of an adverse event.
A second aspect of the disclosure is a system configured to maintain an atmosphere inside a habitat enclosing a work station and shut down one, more than one, or all operational equipment inside and/or outside the habitat (for example as dictated by the client, law, or regulation), in certain embodiments at least operational equipment inside and/or outside the habitat, upon the occurrence of an adverse event, the system comprising:
As used herein “habitat” means a structure enclosing an atmosphere inside of which potentially hazardous work may be performed, either while equipment being worked on (for example, but not limited to pipes, vessels, towers, tanks, reactors, meters, heat exchangers, pumps, compressors) is operating or during equipment downtime. In certain embodiments the structure may be comprised of rigid materials, such as wood, metal, or other structural building material, for example, but not limited to silicone coated fiberglass. Certain exemplary embodiments include those wherein the structure may be comprised of a flexible material, for example a shrink-wrap plastic (polymeric) material. As used herein the term “shrink-wrap” includes, but is not limited to materials that may be heat shrinkable, pressure shrinkable, vacuum shrinkable, chemical shrinkable, or any combination thereof.
These and other features of the methods and systems of the present disclosure will become more apparent upon review of the brief description of the drawings, the detailed description, and the claims that follow. It should be understood that wherever the term “comprising” is used herein, other embodiments where the term “comprising” is substituted with “consisting essentially of” are explicitly disclosed herein. It should be further understood that wherever the term “comprising” is used herein, other embodiments where the term “comprising” is substituted with “consisting of” are explicitly disclosed herein. Moreover, the use of negative limitations is specifically contemplated; for example, certain sensors may trigger audible alarms but not visual alarms, and vice versa. As another example, certain shrink-wrap materials may include one type of chemical additive, but devoid of other additives.
The manner in which the objectives of this disclosure and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:
It is to be noted, however, that the appended drawings of
In the following description, numerous details are set forth to provide an understanding of the disclosed apparatus, combinations, and methods. However, it will be understood by those skilled in the art that the apparatus, systems, and methods disclosed herein may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. All U.S. published patent applications, U.S. patents, U.S. statutes and regulations, and standards referenced herein are hereby explicitly incorporated herein by reference, irrespective of the page, paragraph, or section in which they are referenced. Where a range of values describes a parameter, all sub-ranges, point values and endpoints within that range or defining a range are explicitly disclosed herein. All percentages are by weight unless specified otherwise.
As mentioned herein, LNG facilities, crude oil refineries, petrochemical plants, and other facilities of course may need maintenance either while shutdown or while in operation, the latter sometimes referred to as “on-line.” In either case, work may need to be performed where there is a reasonable chance that an explosive, flammable, and/or poisonous gas or vapor could infiltrate the work site during the course of the work, and such environments are deemed “live environments” herein. The current means of performing this work is to construct a habitat or enclosure where workers can work, or simply do the work without any enclosure but wearing Personal Gas Monitors (PGM). Such habitats may employ shutdown systems for sensing when pressure inside the habitat drops below pressure exterior of the habitat. Such habitats and shutdown systems are designed for positive pressure (above atmospheric pressure) inside the habitat, and may automatically shutdown operations upon negative pressure being sensed inside the habitat.
Safety shut down (SSD) systems and methods are described which reduce or overcome many of the faults of previously known systems and methods. In certain embodiments the logic device and human/machine interface (HMI) of the SSD system may be located at the LNG, refinery, crude oil or petrochemical site and placed either inside or outside the habitat, or both.
The habitat or enclosure of choice is positioned over and around the piece of equipment to be welded, blasted, painted, hot-tapped, insulated, corrosion protected with thermal-sprayed aluminum (TSA) or other thermal spray metal (TSM), or otherwise. The inflow and outflow hoses, conduits, ducts, or chutes are connected to the habitat. Airflow into and out of the habitat is started, as will now be explained more fully with references to the drawing figures.
One or more air extraction units (AEUs) 20, optionally including dust collection units (DCUs) 14, are provided in embodiment 100. In general, as stated elsewhere herein, the primary function of the AEU is to extract more air from the habitat than is provided to the habitat by the HVAC unit(s) to control pressure (P) inside the habitats. A secondary function or benefit is the achievement or promotion of air clarity (for better visibility), and therefore safer conditions inside the habitats.
Any known type of AEU and optional DCU may be employed in practicing the systems and methods of the present disclosure. AEUs may be centrifugal, axial, positive displacement, or combination thereof, arranged in series or parallel. Suitable AEUs may be those available from Cincinnati Fan, Mason, Ohio, U.S.A. under the trade designation MODEL PB Series centrifugal fans, having air capacities up to 4500 CFM, and constructed from type 319 cast aluminum, which is non-sparking, belt drive or direct drive. Other suitable centrifugal fans include MODEL SPB (stamped steel construction); MODEL PBS (fabricated steel); MODELS LM and LMF (forward curve, cast aluminum), and MODEL HP-I pressure blowers. Axial flow air movers use a propeller to draw the air into the fan and discharge it in the same axial direction. Suitable tube axial fans may include those known under the trade designation TAF, BAF, WAF, which designate different bearing features, and are available with cast aluminum or steel props and either belt drive or direct drive, having a capacity ranging from 1500 to 50,000 CFM. Motors used in the fans may be “Totally Enclosed Fan Cooled” (TEFC) or “Totally Enclosed Non-Vented” (TENV) motors, or Explosion Proof (EXP) motors.
Optional DCUs may be selected from bags or bag houses, vertical cartridge filters, and horizontal cartridge filters, whether upflow, downflow, or crossflow, with any cartridge shape (for example, but not limited to circular, oval, polygonal, rectangular, and triangular). The type, size, and size distribution of particulates (dusts) being collected, and the expected flow rates of air in which the dusts are flowing, influences the DCU selection. For smaller projects, such DCU systems are commercially available, such as various high-vacuum cyclone separator dust collection systems available from Oneida Air Systems, Syracuse, New York, U.S.A. These systems typically feature high static air pressure system for CNC, sanding, and other fine dust applications. Complete systems may include heavy-gauge steel cyclone(s), motor(s), wide-pleated spunbond cartridge filter(s), plenum, stand, drum for dust collection, and cord for power. Certain models operate at 230V, 19.5 A, 1-phase motor, with 8 inch inlet, capacity of 2,150 CFM, and operate at from 75 to 81 decibels (dB). Other models operate at 3-phases, and employ variable speed motors operating at from 208 to 230V and 14 A, at 1,789 CFM. Other models may include a rotary airlock, a silencer, and other features. Direct drive systems (7.5, 10, 15, and 20 horsepower (hp) units) and belt/pulley drive systems may be employed in certain embodiments.
In certain embodiments, higher capacity AEUs and DCUs may be employed, such as when thermal spray dust is being collected from a work site. One suitable AEU/DCU may be the unit known under the trade designation TORIT DOWNFLO OVAL, sometimes referred as “DFO”, commercially available from Donaldson Filtration Solutions, Bloomington, Minnesota, U.S.A. As noted on the Donaldson website, thermal spray processes use a heat source, like electric arc spray, plasma or flame spray, to melt metallic or nonmetallic materials and propel them onto a substrate. Managing the overspray in the habitat may be challenging because the particulate (sometimes referred to in the art as “fume”) is very small—typically less than a micron in size. Cartridge filters known under the trade designation TORIT ULTRA-WEB cartridge filters available from Donaldson have a layer of nanofibers that capture particles in the submicron sizes down to 0.3 μm. The nanofiber layer also enables surface-loading, allowing self-cleaning by compressed air pulse of the DFO dust collector. Compressed air pulse self-cleaning is reported by Donaldson to be able to clean the filters effectively-keeping pressure drop low over the life of the filter and extending filter life. The airflow in such units may range from about 100 to about 100,000 cubic feet per minute (CFM) (from about 170 to about 170,000 m3/hr.), and from 1 to 128 filter cartridges, or more. The units may comprise a cyclone pre-cleaner that may include a rotary valve feeding a drum for dust collection, and may include a HEPA post-filter.
Referring again to
Conventionally, a psychrometer of the type including temperature sensors such as platinum resistance bulbs, thermocouples, or thermistors are employed as a humidity sensor for effecting humidity control in constant temperature and humidity environments, such as explained in U.S. Pat. No. 4,911,357. In general, as explained in the '357 patent, relative humidity is computed from the temperature difference between the dry and the wet bulb so that humidity control is affected accordingly. The humidity computing method by such a psychrometric method is known as defined under JIS (Japanese Industrial Standard) 8806. Humidity sensors of other than the psychrometer are, for example, resistive and capacitive humidity sensors, which utilize variations in their electrical characteristics that are caused by adsorption. They include, but are not limited to, an electrolytic lithium chloride humidity sensors, an organic high polymer film humidity sensors, and metallic oxide ceramics humidity sensors.
During a maintenance operation, one or all of T, P, AH, RH, gas or vapor concentrations (or percentages of set point values) inside and/or outside the habitat(s) may be displayed locally on Human Machine Interface (HMI), such as a laptop 50 (
Various flexible conduits 22, 24, such as hoses or other flexible ducts, fluidly connect habitat 2 with various components. For example, in embodiment 100 illustrated schematically in
Referring again to
Referring to
In any case, in exemplary embodiments EGES includes one or more Venturi nozzles (series or parallel, or both) through which the compressed gas passes. The compressor(s) provide a motive force for creating a low-pressure region in the restriction of the Venturi. This low-pressure region is fluidly connected to the habitats through vertical hard duct 26 and horizontal hard ducts 32, and when in operation serves the function of extracting explosive, flammable, and poisonous gases from the habitats. Suitable Venturi gas jet ejectors (sometimes referred to as eductors) are available form a variety of commercial suppliers, such Fox Venturi Products, Dover, New Jersey, U.S.A. Systems may employ motive fluid (compressed air, high or low pressure steam, compressed nitrogen, or other compressed fluid, such as synthetic air supplied from an air separation unit) at pressures ranging from 1 to about 1500 psig (from about 7 to about 1,050 kPa), line sizes ranging from 1 to about 42 inches (2.5 cm to about 100 cm), and to create vacuum ranging from moderate from about 8 to about 12 psia) to extreme (8 psia or less (56 kPa or less), or 6 psia or less (42 kPa or less), or 4 psia or less (28 kPa or less), or 2 psia or less (14 kPa or less), to below 1 psia (below 7 kPa)).
The Venturi gas jet(s) itself may be made of materials selected from metals and plastics. Suitable metals include stainless steel, MONEL, HASTELLOY, titanium, alloy 20, aluminum, or any machinable metal. Suitable plastics include PVC, CPVC, TFE-Lined, PVDF-Lined. Corrosion-resistant alloys may be preferred in certain sour gas or other service where H2S or acid gases or vapors may need removal from habitats, such as T304 stainless steel (or analogs thereof, such as UNS S30400; AMS 5501, 5513, 5560, 5565; ASME SA182, SA194 (8), SA213, SA240; ASTM A167, A182, A193, A194) or T316 stainless steel (or analogs thereof, such as UNS S31600, SS316, 316SS, AISI 316, DIN 1.4401, DIN 1.4408, DIN X5CrNiMo17122, TGL 39672 X5CrNiMo1911, TGL 7143X5CrNiMo1811, ISO 2604-1 F62, ISO 2604-2 TS60, ISO 2604-2 TS61, ISO 2604-4 P60, ISO 2604-4 P61, ISO 4954 X5CrNiMo17122E, ISO 683/13 20, ISO 683/13 20a, ISO 6931 X5CrNiMo17122, JIS SUS 316 stainless steel, or the alloy known under the trade designation MONEL® nickel-copper alloy 400. The composition and some physical properties of MONEL® nickel-copper alloy 400 are summarized in Tables 1 and 2 (from Publication Number SMC-053 Copyright © Special Metals Corporation, 2005). The composition and some physical properties of T304 and T316 stainless steels are summarized in Tables 3 and 4. MONEL® nickel-copper alloy 400 (equivalent to UNS N04400/W.Nr. 2.4360 and 2.4361) is a solid-solution alloy that can be hardened only by cold working. It has high strength and toughness over a wide temperature range and excellent resistance to many corrosive environments. In embodiments where H2S is to be extracted from a habitat, steam jacketed ejectors, maintaining internal gas temps above 280° F. (140° C.) to prevent solidification, may be employed.
athese values also apply to MONEL alloy R-405, the free-machining version of MONEL alloy 400.
Referring once again to embodiment 100 illustrated schematically in
Embodiment 100 and other embodiments may employ, instead of an HVAC unit, a unit that supplies chilled or heated “synthetic air”, in other words, 21% O2, 79% N2, such as could be produced by combining O2 and N2, for example produced by one or more air separation units, which could be membrane units, adsorption units, cryogenic air separation units. As used herein “HVAC unit” is meant to include this option.
Referring now
Safety shutdown systems of the present disclosure and habitats in which they may be used in may be built to meet ISO standards, Det Norske Veritas (DNV) standards, American Bureau of Standards (ABS) standards, American Petroleum Institute (API) standards, or other standards.
Once a habitat and safety shutdown system of the present disclosure is in place at a work area, a power supply will be attached, or of already on board the system (for example in the PLC 40, secure cabinet 56, or HMI 50 as one or more batteries), initiated. The operator may then test the system components, for example sensors, HVCA, AEUs, DCUs, and EGES compressor. Gas and vapor sensors (sometimes referred to as detectors) may be placed at reasonable locations outside the habitat at the air intake and designated points to detect any dangerous gases before they reach the inside of the habitat. Additionally, the operator will ensure the sensors inside and/or outside the habitats are operable to detect any possible gas leaks. The gas detection/shutdown system may be designed as an emergency shutdown system that is capable of giving audio and visual warning based on gas sensor readings at the air intake to and/or inside the habitat to enable manual shutdown or automatic termination. An audio alarm may be provided having at least 90 or at least 95, or at least 100, or at least 105 db sound in a unique sound not to be confused with other alarms or equipment. The shutdown system may be controlled by one or more logic devices (PLC, analog device, or combination thereof), which can be placed inside or outside of the habitat. The shutdown system monitors presence of explosive, flammable, and/or poisonous gases and air pressure within the habitat. The shutdown system controls the HVAC, AEU, DCU, and EGES, and one, more than one, or all operational equipment inside and/or outside the habitat (for example as dictated by the client, law, or regulation), in certain embodiments all operational equipment used within the habitat to perform work (i.e. welding, grinding, blasting, painting, thermal spray application, etc.). In case of detection of explosive, flammable, and/or poisonous gases or increase of pressure inside the habitat above atmospheric pressure, one, more than one, or all operational equipment inside and/or outside the habitat (for example as dictated by the client, law, or regulation), whether electrical, hydraulic, fuel-driven, and/or pneumatic, can and will be shutdown automatically. It is also possible for a worker (preferably a certified technician) to perform a manual shutdown if deemed necessary. Regardless of whether manual or automatic shutdown is employed, the shutdown system will shut down one, more than one, or all operational equipment inside and/or outside the habitat (for example as dictated by the client, law, or regulation) except for the compressor or other source supplying the motive fluid for the EGES. This compressor operates off a separate power system, and may be operated by a diesel, natural gas, or other powered generator.
The electrical connection (voltage and amperage) will be appropriate for the zone rating desired of the system. In certain embodiments one or more electrical cables may be run and connected to an identified power supply at the work site to operate the HMI, gas sensors, HVAC and blowers, AEUs, and optional DCUs. Certain embodiments may employ a dedicated power supply. The identified or dedicated power supply is controlled by the one or more logic devices so that it may be shut down. In exemplary embodiments, systems of the present disclosure may have an electrical isolation (lockout) device on the secure cabinet 56.
In embodiments where connection to one or more remote HMI units is desired, this may be achieved by an intrinsically safe cable and connection so as to allow system components to operate in the required zoned area. If no remote access is required, power to operate the HMI, gas sensors, HVAC, AEUs, and DCUs may be integral to the apparatus, such as batteries, for example, but not limited to, Li-ion batteries. In these embodiments, the power source may be enclosed allowing it to operate in a zoned area (Zone 0 (gases) in accordance with International Electrotechnical Commission (IEC) methods). By “intrinsically safe” is meant the definition of intrinsic safety used in the relevant IEC apparatus standard IEC 60079-11, defined as a type of protection based on the restriction of electrical energy within apparatus and of interconnecting wiring exposed to a potentially explosive atmosphere to a level below that which can cause ignition by either sparking or heating effects. For more discussion, see “AN9003—A User's Guide to Intrinsic Safety”, retrieved from the Internet Jul. 12, 2017, and incorporated herein by reference.
With the habitat in place on a piece of equipment to be worked upon, and a safety shutdown system of the present disclosure connected thereto either by hardwire or wirelessly, the gas sensors display initial concentrations of hazardous gases, while the pressure sensors display initial pressures. As the welding, thermal spray, or other operation proceeds, one or more gas sensors 48 provide a local reading of gas concentration at the location of the gas sensors. Depending on how many gas sensors are employed and where, and how many are activated or working, each provides a gas sensor reading, for example on a display screen having an animated GUI, as illustrated schematically in
In certain embodiments the systems and methods may have the option of shutting down the HVAC and/or starting the EGES automatically when one or more gas sensors and/or one or more pressure sensors register a pre-defined gas concentration or pressure difference, for example more than 1 percent, or more than 2 percent, or more than 5 percent, or more than 10 percent or higher in terms of gas concentration, or more than 10 psi, or more than 20 psi, or more than 50 psi gas pressure or gas pressure differential. In certain embodiments, when the difference reading between two or more gas sensors increases to a pre-defined threshold, the safety shutdown system may automatically shut off one, more than one, or all operational equipment inside and/or outside the habitat (for example as dictated by the client, law, or regulation), whether electrical, hydraulic, fuel-driven, or pneumatic equipment. Alternatively, in certain other method and system embodiments, the EGES may be manually switched on and off depending on which mode (continuous, periodic, or manual) the operator wishes to run the system and perform the method.
In certain embodiments, internal algorithms in the logic device, such as PLC 40, may calculate a rate of increase in concentration, or a rate of increase or decrease in pressure inside the habitat. This may then be displayed or audioed in a series of ways such as “percentage to shutdown” lights or sounds, and the like on one or more GUIs. In certain embodiments, an additional function within a HMI may be to audibly alarm when the calculated pressure rate of increase or decrease reaches a level set by the operator. In certain embodiments this alarm may be sounded inside the habitat, outside the habitat, as well as remote from the habitat, for example in a control room.
Habitats, safety shutdown systems, sensors, logic devices, and associated HVAC, AEU, and EGES should be capable of withstanding long term exposure to probable liquids and vapors, including hydrocarbons, acids, acid gases, fluids (oil-based and water-based), solvents, brine, anti-freeze compositions, hydrate inhibition chemicals, and the like, typically encountered in offshore and onshore processing facilities.
What has not been recognized or realized is a system and method to perform maintenance in a live (on-line) environment on equipment safely and with fewer injuries to workers, in particular in LNG, crude oil refineries, and petrochemical plants. Systems and methods to accomplish this without significant risk to workers are highly desirable. As explained previously, rather non-technical and unsafe systems and methods exist, but personnel do not necessarily favor these methods. The present inventors, however, personally know of the inefficiencies of such practices and the inherently unsafe conditions they create. Multiple accidents have injured workers, and/or exposed workers unnecessarily to noxious fumes, explosions, or fires on working equipment. As an additional safety feature, in practice, for example for offshore use, the habitats and safety shutdown systems of the present disclosure may be painted or otherwise colored or made reflective for ease of recognition.
In alternative embodiments, the habitat need not be rectangular, as illustrated in the drawings, but rather the habitat could take any shape, such as a box or cube shape, elliptical, triangular, prism-shaped, hemispherical or semi-hemispherical-shaped (dome-shaped), or combination thereof and the like, as long as the gas sensors, pressure sensors, safety shutdown system, logic devices, and the like have suitable fittings to connect (either via wired or wireless communication) the to a power source. In yet other embodiments, the habitat may be rectangular, but this arrangement is not strictly necessary in all embodiments. For example, one or more corners of a generally rectangular habitat could be rounded, concave or convex, depending on the desired pressure inside the habitat. It will be understood that such embodiments are part of this disclosure and deemed with in the claims. Furthermore, one or more of the various components may be ornamented with various ornamentation produced in various ways (for example stamping or engraving, or raised features such as reflectors, reflective tape, patterns of threaded round-head screws or bolts screwed into holes in the habitat), such as LNG facility designs, crude oil refinery or petrochemical designs, logos, letters, words, nicknames (for example TUFFss, and the like). The habitat may include optional hand-holds, which may be machined or formed to have easy-to-grasp features for fingers, or may have rubber grips shaped and adorned with ornamental features, such as raised knobby gripper patterns.
Thus the systems and methods described herein provide safety when performing hot work on in service equipment, especially in LNG storage and transfer facilities, crude oil refineries, and petrochemical plants, and with significantly reduced risk of injury and discomfort to workers.
Embodiments Disclosed Herein Include:
Each of the embodiments A, B, and C may have one or more of the following additional elements in any combination:
Appendix: United States Federal Regulations Pertaining to Hydrogen Sulfide Exposure
Hydrogen sulfide exposure is covered under the following OSHA standards:
Worker Exposure Limits (Enforceable)
29 CFR 1910.119 App A and 29 CFR 1926.64 App A, List of highly hazardous chemicals, toxics and reactives (mandatory). Hydrogen sulfide is included in these lists of toxic and reactive highly hazardous chemicals and is considered to present a potential for a catastrophic event at or above 1500 pounds.
Below are standards that include OSHA requirements for evaluating (e.g., process safety, toxic and hazardous substances) and controlling (ventilation, respiratory protection) hydrogen sulfide exposures, including in confined spaces. Industry-specific requirements (construction, shipyard, marine terminals and longshoring) follow.
General Industry
Construction
Shipyard Employment
Marine Terminals
Safety and Health Regulations for Longshoring
Letters of Interpretation (supplementary guidance that clarifies the application of an established Agency policy or procedure)
From the foregoing detailed description of specific embodiments, it should be apparent that patentable systems, combinations, and methods have been described. Although specific embodiments of the disclosure have been described herein in some detail, this has been done solely for the purposes of describing various features and aspects of the systems and methods, and is not intended to be limiting with respect to their scope. It is contemplated that various substitutions, alterations, and/or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the described embodiments without departing from the scope of the appended claims. For example, one modification would be to take an existing habitat structure and modify it to include a safety shutdown system of this disclosure thereon. Another modification would be for habitat suppliers to supply systems with built-in safety shutdown systems in accordance with the present disclosure, including gas sensors and pressure sensors. In other embodiments, the safety shutdown system may be skid or truck-mounted.
The present application claims benefit under 35 U.S.C. § 120 of U.S. nonprovisional patent application Ser. No. 16/145,363, filed Sep. 28, 2018, which in turn claimed benefit under 35 USC § 119 of provisional application No. 62/565,355, filed Sep. 29, 2017, now U.S. Pat. No. 11,105,526, all of which are incorporated by reference herein.
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| Number | Date | Country | |
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| 20210396411 A1 | Dec 2021 | US |
| Number | Date | Country | |
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| 62565355 | Sep 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16145363 | Sep 2018 | US |
| Child | 17463182 | US |
