"DEW POINT REDUCTION SYSTEM"

FIELD OF THE INVENTION

[001 ] The present invention relates to a system and method for conducting works on cryogenic piping through the reduction of the effective dew point in the vicinity of cryogenic piping.

BACKGROUND OF THE INVENTION

[002] Modern industrial applications commonly use what are known as cryogenic piping for transporting gases from location to location. Cryogenic piping is piping that operates at very low temperatures, normally below -5 degrees Celsius.

[003] Cryogenic piping is often used in the oil in gas industry, where gas is transferred from holding tank to holding tank or for processing. As cryogenic piping operate at temperatures at or below freezing, water vapour will condense on the outer surface of the piping. Where the cryogenic piping operates at temperatures below freezing, ice forms on the exterior of the piping.

[004] Dew point is the temperature, when at constant barometric pressure, that water vapour condenses at the same rate as it evaporates. A lower dew point demonstrates a lower temperature at which the rate of condensation and evaporation are equal. If an item is at a lower temperature then the dew point, condensation will form on the item.

[005] To combat the condensation of water vapour onto cryogenic piping, pipework regularly comprises of insulation on the exterior of the piping to prevent the presentation of a surface in to which condensation is generated. The insulation employed normally takes the form of a laminate, multiple material, coating aimed at preventing heat transfer from the pipe to the environment. The insulation effectively allows the outside of the pipe to be at closer to ambient temperature, thereby substantially preventing condensation of water vapour on the pipe.

[006] It must however be understood that dependent on the environmental and operating conditions that the cryogenic piping is exposed to, that instead of water simply condensing on the cryogenic piping, that instead the water condenses on the pipe and then crystal ises to form ice.

[007] Ice formation is a particular problem, a pipe which is covered in ice is places under constant load and conditions which can cause a reduction in fatigue life and in extreme cases failure of the pipe. As ice forms on the exterior of the pip, the compressive load placed on the pipe by the ice may cause the pipe to fail. Additionally, the formation of ice on the exterior of the pipe may also cause a similar formation of ice on the interior of the pipe, which has been known to cause failure in pipes due to blockage.

[008] If as a result of the normal maintenance schedule or in response to some condition, the insulating covering needs to be removed from the cryogenic piping the problem of condensation and ice formation are accelerated. Where condensation is occurring this leads to issues with water run-off, either with water pooling or running off and affecting other areas. If the dew point is low enough ice quickly forms on the exterior of the pipe, the ice effectively preventing any work on the affected area of pipe.

[009] As such it is normal practice to effectively shut down the area where work is to be affected, such that the piping can return to ambient temperature before maintenance or other works are undertaken. As will be appreciated, having to shut down the area of a plant is an expensive undertaking that should be avoided. [0010] The present invention attempts to overcome at least in part the aforementioned disadvantages of previous systems and methods of conducting works on cryogenic pipes.

SUMMARY OF THE INVENTION

[001 1 ] In accordance with one aspect of the present invention there is provided a system for reducing dew point in the vicinity of cryogenic piping comprising an enclosure arranged to enclose cryogenic piping, an environmental control unit and a plurality of gas detectors, characterised in that the environmental control unit is capable of pressurising the enclosure, as well as, lowering the relative humidity within the enclosure such that the dew point is reduced to a temperature at which condensation forming on the cryogenic piping is substantially retarded.

[0012] Preferably, the system further comprises a recirculation unit for

drawing air from within the enclosure and recirculating it into the inlet for the environmental control unit.

[0013] More preferably, the system further comprises an electrostatic

discharge system.

[0014] Even more preferably, the system further comprises a means for

reducing the temperature within the enclosure.

[0015] In accordance with a preferred embodiment, the system further

comprises a plurality of pressurised enclosures arranged to enclose any of the components of the system.

[0016] Preferably, the environmental control unit further comprises a

for controlling the temperature within the enclosure. [0017] Preferably, the enclosure comprises a plurality of panels.

[0018] More preferably, the plurality of panels are arranged to engage in a non-airtight manner,

[0019] Even more preferably, a constant emission of air occurs between the engagements of each of the panels to substantially prevent ingress of gas into the enclosure.

[0020] Preferably, the recirculation unit further comprises a means for

reducing the relative humidity of air passing through the recirculation means.

[0021] The system may also comprise an electrostatic discharge system

comprising a discharge mat which is arranged to form or is on the floor of the enclosure.

[0022] Preferably, the electrostatic discharge system further comprises a plurality of discharge points arranged within the enclosure, the discharge points arranged to enable the connection of machinery and personal to electrical ground.

[0023] The electrostatic discharge system may further comprises a discharge means arranged at each ingress or egress points of the enclosure to prevent machinery and personal entering or leaving the enclosure from carrying electrostatic charge.

1.0024] The system may comprise means for reducing temperature within the enclosure is arranged to draw air from within the enclosure and after cooling deposit air within the enclosure.

[0025] Preferably, the separate enclosures comprises a plurality of panels arranged to engage in a non-airtight manner.

[0026] More preferably, a constant emission of air occurs from engagement of each of the panels to substantially prevent egress of gas into the separate enclosure.

[0027] Preferably, the environmental control unit is capable of raising the temperature within the enclosure.

[0028] Preferably, the environmental control unit comprises a desiccant rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0030] Figure 1 is a block diagram of a system in accordance with the present invention

[0031] Figure 2 is a block diagram of the system of figure 1 further comprising a sublimation unit

[0032] Figure 3 is a block diagram of the system of figure 2 further comprising a recirculation means.

[0033] Figure 4 is a block diagram of the system of figure 3 further comprising an electrostatic discharge system.

[0034] Figure 5 is a block diagram of the system of figure 4 further comprising a separate enclosure arranged to enclose the environmental control unit.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Referring to the Figures, there is shown a system 10 for reducing the dew point in the vicinity of cryogenic piping. In accordance with this exemplary embodiment of the invention the system 10 comprises an enclosure 12, an environmental control unit 14 and a plurality of gas detectors 18. [0036] The enclosure 12 is preferably arranged to comprise a plurality of panels 20, which are arranged to engage such that interconnection between each panel 20 forms a non-airtight seal between engaging panels. Preferably, the panels 20 are arranged such that there are interconnecting primary and secondary fasteners that engage in a complementary manner.

[0037] The panels 20 are bought into close abutting contact with each other to form the enclosure 12 around the cryogenic piping. Preferably, the enclosure 12 would be formed such that sufficient room is provided to allow work to be comfortably undertaken. The arrangement of the panels 20 is dependent on the particular deployment being undertaken and will change as required. If required the enclosure 12 may be arranged to enclose a number of pipes, including those not requiring to be worked upon, to ensure sufficient space within the enclosure for necessary work to be completed.

[0038] Preferably, the panels are of the type disclosed in Australian Patent Application Number 2012205257.

[0039] The system 10 also comprises a plurality of gas detectors 18, preferably, the gas detectors are arranged at a number of locations throughout the system. The gas detectors 18 acting to detect hazardous vapours that may have entered the enclosure. By way of example, when the enclosure, is situated in the vicinity of an LPG facility, a plurality of gas detectors 18 capable of detecting LPG will be arranged to prevent the incidental egress of LPG into the enclosure. However, it should be appreciated that gas detectors 18 may be capable of detecting a number of different gases in their vivinity.

[0040] Preferably, the gas detectors 18 also comprise an alarm system such as a siren, which sound in the event of the detection occurring. [0041] More preferably, the plurality of gas detectors 18 are arranged to communicate wireiessly with each other. In the event that any of the plurality of detectors 18 detect unwanted gasses, the alarms associated with each of the plurality of detectors 18 being arranged to sound to ensure that all personal are aware of the ingress of unwanted gasses into the system 10.

[0042] Preferably, the system 10 further comprises an anti-static charge system 16 which preferably is arranged within the enclosure 12. The anti-static charge system 16 preferably comprises an electromagnetic discharge mat (not shown), arranged as the floor of the enclosure 12, which is electrically connected to be grounded to an earth point, such that anything electrically connected to the discharge mat 22 is held at earth potential. The anti-static charge system 16 may further comprise a number of discharge points (not shown), which are arranged at locations inside the enclosure 12, to allow the connection of machinery and/or personal.

[0043] In accordance with another preferred embodiment of the invention, the anti-static charging system 16 may further comprise discharge means (not shown). The discharge means are arranged at ingress and egress points of the enclosure 12. The discharge means being arranged to ensure, that personal entering or exiting the enclosure are returned to a ground potential.

[0044] The anti-static charging system 16 acts to ensure that there are no incidental static discharges, either within or out of the enclosure.

[0045] In accordance with a preferred embodiment of the invention, the system 10 further comprises a sublimation unit 26. Preferably, the sublimation unit 26 is arranged to be activated once sublimation of all ice and evaporation of all water inside the enclosure 12 has been converted into water vapour.

[0046] In accordance with another preferred embodiment of the invention, the system 10 further comprises a recirculation unit 28. which is arranged to re- circulate air with a low relative humidity from the enclosure 12 back into the intake of the environmental control unit 14.

[0047] In accordance with yet another preferred embodiment of the invention, the system 10 may comprise a plurality of fans 30, arranged throughout the system to increase the rate of airflow within the system.

[0048 J In use, the system 10 of the present invention acts to control the dew point in the vicinity of cryogenic piping, such that the rate of condensation forming on the piping is substantially reduced.

[0049] A plurality of panels are bought together in form an enclosure 12. The enclosure 12 is arranged around cryogenic piping which requires a controlled environment to be placed around it, such that inspection or works can be undertaken.

[0050] The enclosure 12 is arranged to be in communication with an environmental control unit 14, such that the environmental control unit 14 is able to supply a constant stream of dehumidified air to the enclosure 12. The environmental control unit 14 being arranged to provide sufficient air-flow such that the interior of the enclosure 12 is at a pressure higher than atmospheric pressure.

[0051 ] The arrangement of the panels 20 of the enclosure 12, ensure that all seams are arranged such that once pressurised a continuous stream of air is emitted from the enclosure 12. This continuous emission of air from the seams between panels substantially prevents the ingress of outside gasses from entering the enclosure 12.

[0052] The process of dehumidifying the air normally results in a net increase of the temperature of the air above the ambient air temperature. Advantageously this results in faster sublimation of any ice or water vapour in the enclosure 12. It is expected that the temperature within the enclosure 12 will exceed 40 degrees Celsius in use.

[0053] Preferably, the increased internal temperature is sufficiently high enough to allow ice to sublimate directly to vapour.

[0054] The system 10 operates to control the dew point within the climate controlled enclosure 12, such that water evaporates faster than it condenses on the cryogenic piping. In effect be reducing the relative humidity of the air supplied to the climate controlled enclosure 12 and increasing the temperature inside the enclosure 12, the system 10 of the present invention causes the dew point within the enclosure 12 to lower.

[0055] Preferably, the system 10 is able to reduce the dew point within the enclosure to a temperature at which condensation forming on the cryogenic piping is substantially retarded.

[0056] More preferably, the system 10 is able to reduce the dew point to a temperature below which the cryogenic piping the enclosure surrounds is operating at, thereby effectively preventing condensation.

[0057] The enclosure 12 is arranged such that it is in electrical communication with the electro-static charge system 16. Preferably, the electro-static charge system 16 is arranged such that the anti-static discharge mat 22 forms or is on the floor of the enclosure 12.

[0058] Preferably, the anti-static discharge system 16 has arranged at locations throughout the enclosure 12 a plurality of discharge points. The discharge points being arranged to be in communication with an earth point. The plurality of discharge points being further arranged to allow the connection of earth strap, such as equipment can effectively be grounded or personal within the enclosure can connect individual static discharge connections between themselves and one of the discharge points.

[0059] More preferably, the anti-static discharge system 16 further comprises discharge means 24 in the form of ingress and egress curtains, which are arranged at each entry and or exit point of the enclosure 12. The ingress and egress curtains being arranged such that personal inside the enclosure will have to pass through the curtain to enter or exit the enclosure. The ingress and egress curtains therein acting to substantially prevent personal from developing a static charge while in the enclosure and then inadvertently causing a static discharge after leaving the enclosure 12.

[0060] As will be appreciated human personal, cannot work at temperatures above 40 degrees Celsius for any length of time. Therefore in accordance with a preferred embodiment of the invention the system 10 further comprises a sublimation unit 26. The sublimation unit 26 being arranged to draw air from within the enclosure 12, cool it and then pass it back into the enclosure 12. Ideally, the sublimation unit 26 should be able to sufficiently cool the air within the enclosure to around 30 degrees Celsius.

[0061] By drawing already dehumidified air from within the enclosure 12, the sublimation unit 26 is able to cool the interior of the enclosure without adversely introducing additional water vapour to the enclosure.

[0062] Preferably, the system 10 further comprises a recirculation unit 28 arranged to draw air from inside the enclosure 12 into the inlet of the environmental control unit 1 . The air drawn from within the enclosure is passed back into the inlet of the environmental control unit, thereby taking low humidity air from within the enclosure and further dehumidifying it.

[0063] As will be apparent to the skilled addressee, by recirculating air from within the enclosure 12 the system 10 benefits in a number of ways. Firstly, the air taken from the enclosure 12 is further dehumidified, in effect acting as a means for removing moisture from within the enclosure 12. Further, it will be apparent that by drawing already low humidity air from the enclosure, that the effective relative humidity of the airflow issuing from the environmental control unit 14 will be lower. Additionally, the energy used to reduce the humidity of air supplied to the chamber will be lower as less energy need be expended to achieve the same relative humidity.

[0064] Preferably, the recirculation unit 28 draws air from a location remote from the outlet of the sublimation unit 26 if fitted.

[0065] Even more preferably, the recirculation unit 28 is arranged to draw air from the enclosure at a location as remote as possible from the outlet of the sublimation unit 26 if fitted.

[0066] In accordance with a preferred embodiment of the present invention the system is arranged to include a plurality of independent enclosures 30, which are arranged to enclose any of the components of the system which are external to the enclosure 12. For example, the environmental control unit 14. Such an arrangement being necessary for operation equipment in situations such as when work is being undertaken in the confines of an LPG processing facility or any other facility where flammable materials are stored or processed.

[0067] Preferably, all components of the system 10 would carry an EX rating allowing them to be used in the presence of flammable materials, without explosion risk. Continuing the example of the environmental control unit 14 which not EX rated, the environmental control unit 14 will be housed within the confines of the enclosure 30.

[0068] The enclosure 30, preferably, comprising a plurality of panels 32 similar to the panels of the climate controlled enclosure 12. Each of the panels being provided with a primary and secondary fastener arranged such that a non-airtight seal is created between adjacent panels 32.

10069] The enclosure 30 being in communication with a source of air flow such as a fan 32. The fan providing sufficient air flow to ensure that the interior of the enclosure is at a high pressure then the outside environment such that there is a positive emission of air from each of the joints between the panels of the enclosure 30

[0070] As required, other components in the system 10 may be arranged within separate enclosures 30 as required. Each of the enclosures 30 being arranged to ensure operation of EX rated equipment within hostile environments which contain flammable gasses or liquids.

[0071] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.