AU2020203000A1 - Burners and immersion heating systems for bitumen tankers - Google Patents

Abstract

A gas burner is disclosed comprising a housing defining an elongate throat for receiving combustion gas and mixing the combustion gas with an oxidant. An output of the burner is provided at an end of the throat; and the housing further defines a pre-heating chamber extending along a length of the throat. The pre-heating chamber includes an input, for receiving the combustion gas, and an output, for providing the combustion gas after it has been pre heated. The input and the output are spaced at least along a length of the pre-heating chamber, and the pre-heating chamber is configured to pre-heat and/or vapourise the combustion gas prior to injection into the throat. A bitumen tanker, including the gas burner is also disclosed. Fig 1 for publication. 2/7 C(N COO co IC) (o (NN CO\ o 0) CN o cxco IC) LOI 000 CO 0m CN 0 cxco 00 O 00 (N/I

Description

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(N/I BURNERS AND IMMERSION HEATING SYSTEMS FOR BITUMEN TANKERS TECHNICAL FIELD

[0001] The present invention relates to burners and immersion heating systems, for bitumen tankers.

BACKGROUND ART

[0002] Bitumen is often used for road construction, where it is used in both sprayed sealing and asphalt applications. Bitumen must generally be heated for it to be sufficiently flowable to be discharged from a tank and be applied to a surface in road construction able to be handled. As such, bitumen is generally transported "hot" in bitumen tankers, which include heaters to heat the bitumen.

[0003] Bitumen tankers of the prior art generally include heating tubes, and a burner is used to blow hot combustion products through the heating tubes to thereby heat the bitumen in the tanker. As such, the heating tubes function as a heat exchanger from the hot combustion products blown therethrough and the bitumen in the tanker.

[0004] A problem with such bitumen tankers of the prior art is that they are difficult to operate. As an illustrative example, the burners are very powerful, and thus operate with high rates of gas flow. As a result, the burners are hard to light, and are prone to backfiring, which is clearly undesirable.

[0005] Furthermore, the burners and tankers of the prior art must be carefully monitored. As an illustrative example, if a flame of the burner goes out, gas will continue to flow, filling the heat tubes, which can cause an explosion risk. As such monitoring is a manual process that cannot easily be automated, and it is reliant on careful observation by an operator, which can be unreliable.

[0006] While attempts have been made to incorporate safety features into tankers, it is difficult to do so. As a result, the tankers currently in use are generally heavily reliant on skilled operators and manual intervention. Accordingly, operators, and particularly those with less experience with the tankers, are working in an unsafe environment, which is undesirable, not only for the operators directly, but also those in the vicinity of the tanker.

[0007] As such, there are some clear shortcomings with burners and immersion heating systems for bitumen tankers.

[0008] The reference to prior art in this specification is not and should not be taken as an acknowledgment or any form of suggestion that the referenced prior art forms part of the common general knowledge in Australia or in any other country.

SUMMARY OF INVENTION

[0009] The present invention is directed to burners, immersion heating systems, bitumen tankers and fuel control systems for bitumen tankers, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

[0010] The term "bitumen tanker" is used broadly to encompass tankers configured to transport bitumen (commonly referred to simply as bitumen tankers), as well as tankers configured to spray bitumen (commonly referred to simply as bitumen sprayers).

[0011] With the foregoing in view, in a first aspect the present invention resides broadly in a gas burner comprising a housing defining an elongate throat for receiving combustion gas and mixing the combustion gas with an oxidant, wherein an output of the burner is provided at an end of the throat; the housing further defining a pre-heating chamber extending along a length of the throat, the pre-heating chamber including an input, for receiving the combustion gas, and an output, for providing the combustion gas after it has been pre-heated, wherein the input and the output are spaced at least along a length of the pre-heating chamber, and wherein the pre heating chamber is configured to pre-heat and/or vapourise the combustion gas prior to injection into the throat.

[0012] Advantageously, by providing a pre-heating chamber where the input and the output are spaced at least along a length of the pre-heating chamber, and wherein the pre-heating chamber extends along a length of the throat, the combustion gas is able to be pre-heated in a consistent manner. In particular, the combustion gas may be forced along a length of the throat, which may provide a consistent path of combustion gas.

[0013] Preferably, the input of the pre-heating chamber is located on an opposite side of the pre-heating chamber than the output.

[0014] Preferably, the input and/or the output comprises tubes that extend into the pre heating chamber. Suitably, the input and output extend different lengths into the pre-heating chamber to thereby provide spacing along a length of the pre-heating chamber.

[0015] Preferably, the pre-heating chamber extends around a periphery of the throat.

[0016] Preferably, the housing comprises an inner tubular body and an outer tubular body, wherein the pre-heating chamber is defined at least in part between the inner tubular body and the outer tubular body.

[0017] Preferably, the throat is defined by the inner tubular body. The throat may be defined at least in part by an inside of the inner tubular body, and the pre-heating chamber may be defined at least in part by an outside of the inner tubular body.

[0018] Preferably, end plates couple the inner tubular body and the outer tubular body. The end plates may be annular in shape, wherein an outer diameter of each end plate corresponds to a size of the outer tubular body, and an inner diameter of each end plate corresponds to a size of the inner tubular body.

[0019] Preferably, the throat extends beyond the pre-heating chamber at the end of the throat. Preferably, the throat extends prior to the pre-heating chamber at an inlet of the throat.

[0020] The burner may optionally comprise a venturi burner.

[0021] Preferably, the burner is configured to receive the combustion gas at or near an inlet of the throat. Preferably, the burner is configured to draw in air at the inlet of the throat when the combustion gas is injected into the throat.

[0022] The burner may comprise a nozzle, configured to inject combustion gas at or near the inlet of the throat. Suitably, the nozzle may be configured to inject combustion gas under pressure. The nozzle may be configured to inject vaporised combustion gas at a pressure of between about 7kPa and 220kPa. Suitably, the nozzle may be configured to inject vaporised combustion gas at a pressure of between about 80 - 160kPa.

[0023] The nozzle may comprise an aperture about 2-3mm in diameter. The nozzle may be positioned between about 148mm and 168mm from an outlet of the burner.

[0024] The output may be configured to enable one or more intermediary elements to be coupled intermediate the output and the nozzle. The output may include a coupling. The nozzle may include a coupling. The one or more intermediary elements may be coupled between the output and the coupling by the couplings.

[0025] Preferably, the housing is substantially uniform in cross section along at least a portion of its length.

[0026] Preferably, the housing is substantially cylindrical in shape.

[0027] Preferably, the throat is about 50mm-60mm in diameter. The throat may comprise 50NB pipe. Preferably, an outer wall of the housing is about 90-110mm in diameter. The outer wall of the housing may comprise 90NB pipe. The throat and the outer wall of the housing may comprise schedule 40 pipe. The outer wall of the housing and the throat may be joined by end plates that may be about 4mm thick.

[0028] The throat may have a cross sectional area that is approximately half the size of the corresponding cross section of the heating chamber.

[0029] The throat may be about 180mm long. The heating chamber may be about 125mm long. The heating chamber may extend along at least half a length of the throat.

[0030] The input and the output may be spaced by at least half the length of the heating chamber. The input and the output may be positioned adjacent to respective ends of the chamber.

[0031] Preferably, the input and the output are spaced by around 85mm along a length of the chamber.

[0032] Preferably, the combustion gas comprises LPG and the oxidant comprises oxygen in air.

[0033] The pre-heating chamber may be configured to receive liquid LPG and vaporise the liquid LPG.

[0034] The burner may be formed of tubular steel and metal plates, which are welded. The steel may comprise stainless steel. The steel may be coated. The steel may be coated subsequent to welding. The steel plates may be stamped or cut.

[0035] Preferably, the burner meets Australian Standard (AS) 1375-2013 Industrial Fuel Fired Appliances and AS 3814:2018 Industrial and Commercial Gas-fired Appliances.

[0036] Preferably, the burner has a nominal output of about 300 - 600MJ/hour.

[0037] In a second aspect, the present invention resides broadly in a bitumen tanker, including a burner, e.g. a gas burner, configured to heat bitumen in the tanker, wherein fuel is configured to be provided to the burner at a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, wherein the first predefined rate is lower than the second predefined rate.

[0038] Advantageously, by including a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, the burner is less likely to backfire, and more easily and safely lit. Furthermore, as the rates are predefined, an operator need not manually select appropriate rates for lighting the burner and running the burner.

[0039] The bitumen tanker may include a burner as defined in a preceding aspect of the disclosure or invention. In particular, the burner may include any one or more of the optional features of the burner defined and described in the first aspect of the invention.

[0040] Preferably, the fuel is liquid petroleum gas (LPG). Preferably, the bitumen tanker includes an LPG tank for storing the fuel. The LPG tank may be refillable without removing the LPG tank from the bitumen tanker. Suitably, the LPG tank is associated with one or more fill points.

[0041] Preferably, the bitumen tanker is configured to be manually switchable between the first and second predefined rates. Suitably, one or more valves in proximity to the burner may be opened and/or closed to switch between the first and second predefined rates. The valves may comprise a valve, e.g. a ball valve with a handle, to enable the valve to be manually opened and closed.

[0042] Preferably, the bitumen tanker includes a low-pressure path, for providing fuel to the burner at the first predefined rate, and a high-pressure path, for providing fuel to the burner at the second predefined rate. Suitably, the low and high-pressure paths are provided in parallel.

[0043] The low-pressure path may be associated with a regulator, configured to regulate a pressure of the gas in the low-pressure path. The high-pressure path may similarly be associated with a regulator, configured to regulate a pressure of the gas in the high-pressure path. The regulator in the high-pressure path may be configured to regulate the fuel at a higher pressure than the regulator in the low-pressure path.

[0044] The low-pressure path may include a valve, configured to enable fine adjustment of the flow from the low-pressure path. The valve may comprise a needle valve.

[0045] The bitumen tanker may include a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame of the burner goes out.

[0046] Preferably, the flame failure valve is configurable to open and close without requiring coupling to a power supply.

[0047] Preferably, the bitumen tanker includes a thermocouple, in proximity to the burner, the thermocouple configured to automatically control the flame failure valve to enable the supply of fuel to the burner when heat from the burner heats the thermocouple. Preferably, the flame failure valve is closed unless the thermocouple is heated. Preferably, the thermocouple includes a cover, for protecting the thermocouple from the burner. The cover may comprise a metal cover, configured to protect the thermocouple from direct heat from the burner.

[0048] Preferably, the burner includes a body including a channel for pre-heating the fuel. More preferably, the channel is for vaporising the fuel using heat from the burner.

[0049] Preferably, the flame failure valve is configured to isolate a supply of fuel from the burner after the fuel is pre-heated. Such configuration may provide less wear on the valve, and requires less energy than a valve that operates on liquid fuel and that freezes.

[0050] The burner may include an input line, for receiving the fuel for heating, and an output, for outputting the heated fuel.

[0051] The flame failure valve may be at least about 30cm from the burner.

[0052] The bitumen tanker may include a pressurised air system, and an air actuated (pneumatic) valve, configured to close a supply of fuel to the burner based upon air pressure provided by the pressurised air system.

[0053] The pressurised air system may be configured to prevent the burner from being engaged while the tanker is in motion.

[0054] The tanker may include a fire safety element, configured to close a supply of fuel to the burner if a fire or bitumen spill is detected. The fire safety element may comprise plastic piping which is configured to melt if there is a fire or bitumen spill. The plastic piping may be configured to cut off an air supply to the pneumatic valve, thereby closing a supply of fuel to the burner.

[0055] The bitumen tanker may include a reservoir for receiving the bitumen, and a heater tube that extends through the reservoir, wherein the burner is configured to heat the heating tube, to thereby heat the bitumen in the reservoir.

[0056] The bitumen tanker may be configured to transport the bitumen. The bitumen tanker may include a sprayer, configured to spray the bitumen, e.g. directly onto a road surface. The bitumen tanker may be configured to transport and spray the bitumen.

[0057] In a third aspect the present invention resides broadly in a bitumen tanker, including a burner configured to heat bitumen in the tanker, the bitumen tanker including a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame of the burner goes out.

[0058] Preferably, the flame failure valve is configurable to open and close without requiring coupling to a power supply.

[0059] Preferably, the bitumen tanker includes a thermocouple, in proximity to the burner, the thermocouple configured to automatically control the flame failure valve to enable the supply of fuel to the burner when heat from the burner heats the thermocouple. Preferably, the flame failure valve is closed unless the thermocouple is heated.

[0060] Preferably, the burner includes a body including a channel for pre-heating the fuel. More preferably, the channel is for vaporising the fuel using heat from the burner.

[0061] Preferably, the flame failure valve is configured to close a supply of fuel to the burner after the fuel is pre-heated. Such configuration may provide less wear on the valve, and requires less energy than a valve that operates on liquid fuel and that freezes.

[0062] The burner may include an input line, for receiving the fuel for heating, and an output, for outputting the heated fuel.

[0063] The flame failure valve may be at least about 30cm from the burner.

[0064] In a third aspect the present invention resides broadly in a fuel control system for a bitumen tanker, the bitumen tanker including a burner configured to heat bitumen in the tanker using the fuel.

[0065] In a fourth aspect the present invention resides broadly in a fuel control system for a bitumen tanker, the bitumen tanker including a burner configured to heat bitumen in the tanker using the fuel, wherein the fuel control system is configured to provide fuel to the burner at a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, wherein the first predefined rate is lower than the second predefined rate.

[0066] In a fifth aspect the present invention resides broadly in a fuel control system for a bitumen tanker, the bitumen tanker including a burner configured to heat bitumen in the tanker using the fuel, wherein the fuel control system includes a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame of the burner goes out.

[0067] In a sixth aspect, the invention resides broadly in an immersion heating system including a burner configured to heatfluid in a reservoir by one or more immersion tubes, wherein fuel is configured to be provided to the burner at a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, wherein the first predefined rate is lower than the second predefined rate.

[0068] In a seventh aspect, the invention resides broadly in an immersion heating system including a burner configured to heat fluid in a reservoir by one or more immersion tubes, the system including a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame of the burner goes out.

[0069] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

[0070] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

[0071] Various embodiments of the invention will be described with reference to the following drawings, in which:

[0072] Figure 1 illustrates a simplified side view of a bitumen tanker, according to an embodiment of the present invention.

[0073] Figure 2 illustrates a schematic of the gas components of the tanker of Figure 1, including gas control components, according to an embodiment of the present invention.

[0074] Figure 3 illustrates a top view of a portion of the gas components illustrated in Figure 2, including a burner.

[0075] Figure 4 illustrates a side view of the gas components of Figure 3.

[0076] Figure 5 illustrates cooling coil, according to an embodiment of the present invention.

[0077] Figure 6 illustrates a side view of a cover for protecting a thermocouple, according to an embodiment of the present invention.

[0078] Figure 7 illustrated a top view of the cover of Figure 6.

[0079] Figure 8 illustrates a plan view of a burner according to an embodiment of the present invention.

[0080] Figure 9 illustrates an end view of the burner of Figure 8.

[0081] Figure 10 illustrates a plan view of the burner of Figure 8 showing internal components in dashed lines.

[0082] Figure 11 illustrates an end view of the burner of Figure 8 showing the internal components in dashed lines.

[0083] Figure 12 illustrates an exploded view of components that may be joined to form a burner, such as the burner of Figure 8, according to an embodiment of the present invention.

[0084] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way.

DETAILED DESCRIPTION

[0085] Figure 1 illustrates a simplified side view of a bitumen tanker 100, according to an embodiment of the present invention. The bitumen tanker 100 is safer than prior art tankers in that it enables an operator to more safely light a burner thereof, it automatically prevents gas from being discharged from the burner when not lit, and provides automatic shut off of gas in a variety of scenarios, as outlined below.

[0086] The bitumen tanker 100 is illustrated in simplified form for the sake of clarity, and thus does not illustrate a variety of well-known features of prior art tankers and trailers, such as axles, draw bar, lights, frames and the like. The skilled addressee will readily appreciate that the tanker 100 may include these features, which may be incorporated by matter of routine, and such incorporation does notform part of the present invention. In fact, priorart bitumen tankers, such as bitumen tankers made by Holmwood Highgate (Aust) Pty Ltd of Loganholme, QLD, Australia, may be adapted to form tankers of the present invention.

[0087] The tanker 100 includes a bitumen tank 105, for receiving and heating bitumen. The bitumen tank 105 is elongate in shape, and the tanker 100 is substantially defined in shape by the bitumen tank 105. The bitumen tank 105 may be insulated, to enable "hot" bitumen to be transported without significant loss of heat thereof.

[0088] A heating (immersion) tube 110 extends through the tank 105, and is in contact with bitumen inside the tank 105, and a burner 115 is configured to blow hot combustion products through the heating tube 110 to thereby heat the bitumen in the tank 105. The heating tube 110 extends from an inlet, adjacent to the burner 115, along a length of the tank 105, across the tank 105, and then back along the length of the tank 105 to a flue 120.

[0089] The lengths of heating tube 110 are parallel, and this ensures that the heat from the burner 115 is transferred to the bitumen from the hot combustion product of the burner 115 in an efficient manner. The skilled addressee will, however, readily appreciate that the heating tube 110 may take any suitable shape, and may extend back and forward along the length of the tank 105 multiple times, for example.

[0090] The burner 115 is coupled to a liquid petroleum gas (LPG) tank 125 by a gas control system 130, which enables accurate control of the LPG. The gas control system 130 may simplify and increase safety when lighting the burner, as outlined below. Furthermore, the gas control system may isolate the gas supply when the flame of the burner 115 goes out, when there has been an overflow of hot bitumen, or when the tanker 100 is not properly parked.

[0091] Figure 2 illustrates a schematic diagram 200 of the gas components of the tanker 100, including the gas control system 130, according to an embodiment of the present invention. Figure 3 illustrates a top view of a portion of the gas components illustrated in Figure 2, including the burner 115, and Figure 4 illustrates a side view of the gas components of Figure 3.

[0092] As outlined above, the tanker includes functionality to enable safe lighting of the burner 115. This is achieved using a low-pressure pathway 205, which may be selectively coupled to the burner 115, to provide low-pressure gas to the burner 115 when lighting the burner.

[0093] As best illustrated in Figure 4, the low-pressure pathway 205 includes a low-pressure regulator 210, which is configured provide the low-pressure environment to the low-pressure pathway 205, and a manually actuable valve 215, to enable the low-pressure pathway 205 to be opened and closed. A needle valve 220 is provided in the low-pressure pathway, after the regulator 210, to enable precise regulation of flow through the low-pressure pathway 205.

[0094] The low-pressure pathway 205 is in parallel to a high-pressure pathway 225, which may be selectively coupled to the burner 115, to enable the burner 115 to operate in a heating configuration. The high-pressure pathway 225 includes a high-pressure regulator 230, which is configured provide the high-pressure environment to the high-pressure pathway 225, and a manually actuatable valve 235, to enable the high-pressure pathway 225 to be opened and closed.

[0095] In use, the valves 215 and 235 are initially closed, which blocks both the low and high-pressure pathways 205, 225. As such, no gas reaches the burner 115. The operator may open the valve 215 by rotating a handle thereof, thereby opening the low-pressure pathway, resulting in low rate of gas flow at the burner 115. The operator may then light the burner 115, which is much easier, and much less prone to backfiring or explosion, given the low rate of gas flow, particularly when the burner is cold. At this point, the burner is lit, but is burning at a low rate, and thereby not heating the bitumen in the tanker 100 in any substantial way.

[0096] The operator may then open the valve 235 by rotating a handle thereof, thereby opening the high-pressure pathway, resulting in a high rate of gas to the burner 115. In such configuration, the burner heats the bitumen by blowing hot combustion product into the heating tube. While various different types and sizes of burners may be used, it is expected that the burner be able to produce between about 0.4-1.5 GJ/hr in such heating configuration.

[0097] The operator may later close the valve 235, upon which the burner 115 will return to a low rate burn, much like a pilot light. The valve 215 may also be closed to turn off the burner 115 entirely.

[0098] Traditionally, such burners have been provided with just a single high-pressure path and a single valve, which has meant that any control that the operator has on the gas flow has been limited to a partial opening of a valve on the high pressure line only. Such control is very coarse, and as such, results in gas passing through the burner at rates which are not controlled by the operator, which can cause difficulty in lighting the burner. Furthermore, installing a valve with fine control directly on the high pressure line is generally not possible, as such valves restrict the flow of gas, even when fully open. Thus, the solution is to create a low pressure path in parallel with a high pressure path. As best illustrated in Figure 3, the regulated LPG is provided to an input 240 of the burner 115 in liquid form, after which the LPG travels through a body 115a of the burner, where it is heated and vapourised. The vapourised LPG then travels out of the body 115a through a vapourised gas output 245, down to a flame failure valve 250, and then back up to an injector 255 where the vapourised gas is injected into an opening 260 of the burner 115.

[0099] The injector 255 is supported by a spacer 265, which is coupled to the input 240, such that the injector 255 is spaced from the opening 260 and is centrally positioned with respect to the opening 260.

[00100] The opening 260 of the burner 115 comprises a venturi or cylindrical pipe section, where air (from the surrounding atmosphere) is induced, mixed with the vaporised LPG, and is burnt at an outlet 270 of the burner 115.

[00101] A thermocouple 275 is positioned adjacent to the outlet 270 and is coupled to the flame failure valve 250, such that when a flame is present at the outlet the heat thereof applied to the thermocouple 275 generates a voltage, which is used to keep the flame failure valve 250 open. Conversely, if the flame were to go out, the flame failure valve 250 would close shutting off fuel to the burner.

[00102] Similarly, a bitumen over temperature sensor/controller 278, which is positioned in the tank 105 to measure a temperature of the bitumen, is coupled to the flame failure valve 250 to similarly close the valve 250 to stop the burner should the temperature of the bitumen exceed a temperature threshold.

[00103] The flame failure valve 250 has a bypass in the form of a button, which enables manual bypass of the flame failure valve 250, to enable the burner 115 to be lit. In use, the manual bypass would be activated for a short time during and after lighting the burner 115 to keep the flame failure valve 250 open until the thermocouple 275 has reached temperature and is able to keep the valve 250 open itself.

[00104] By having an outlet 245 for vaporised gas from the burner 115 configured in such manner enables a thermocouple 275 and flame failure valve 250 to be used, as it is operating on vaporised gas (rather than liquid gas). The use of such valves on the input line 240 close to the burner 115 is not possible, as these areas get very cold and freeze, which can cause damage to the valve. Further the valves may be exposed to liquid rather than vapour and the voltage from the thermocouple 275 may not be sufficient to operate the valve in such circumstances.

[00105] In some circumstances, the vapour in the outlet 245 is too hot for the valve 250. As an illustrative example, certain vapour valves have an operating range of up to about 150°C, and the vapour in the outlet may be warmer than this in some scenarios. As such, a heat exchanger or cooler may be added to the outlet 245 to cool the vapour.

[00106] Figure 5 illustrates cooling coil 500, according to an embodiment of the present invention. The cooling coil 500 may be positioned at the outlet 245 between the burner 115 and the valve 250 to cool (i.e. reduce a temperature) of the vapour.

[00107] The cooling coil 500 comprises stainless steel piping 505, which is bent to form a helical coil. The helical coil has a much larger surface area than a straight pipe extending directly between two points, and as such, heat from the vapour is more readily able to transfer to the atmosphere, thereby cooling the vapour. The piping may be formed to extend from the burner 115 to the valve 250 without any joins.

[00108] Such cooling coils 500 have been shown to reduce the temperature of the vapour at the outlet from about 170°C to about 100°C.

[00109] In alternative embodiments, other types of coolers or heat exchangers may be used to cool the vaporised gas. In one specific embodiment, a heat exchanger may be used to transfer heat from the hot outlet 245 to the cold inlet 240. As an illustrative example, the heat exchanger may comprise a counterflow heat exchanger where the vapour of the hot outlet 245 flows through a reservoir in which the cold inlet 240 gas flows (or vice versa).

[00110] The tanker 100 may include a cover for protecting the thermocouple 275 from the flame of the burner, which may also be sized and shaped to improve the performance of the thermocouple 275.

[00111] Figure 6 illustrates a side view of a cover 600 for protecting the thermocouple 275, according to an embodiment of the present invention. Figure 7 illustrated a top view of the cover 600.

[00112] The cover 600 comprises a tubular body 605, and is configured to receive the thermocouple 275 within the tubular body. An opening 610 is provided in an upper side of the tubular body 605, exposing an upper portion of the thermocouple 275 at an end thereof. A support 615 is provided at an opposite end of the body 605 to the opening 610, and is issued to attach the thermocouple 275 to the cover 600, and the cover to the burner 115. The support 615 includes an aperture through which a portion of the thermocouple 275 extends, and the thermocouple is clamped to the support using first and second nuts.

[00113] The cover 600 is positioned such that the burner 115 is located at an underside of the cover, and as such the cover 600 protects the thermocouple 275 from the flame. The cover also, being formed of metal (e.g. stainless steel), provides a heat buffer, to prevent the gas from inadvertently being turned off from a gust of cold wind against the thermocouple 275.

[00114] Now turning back to Figure 2, the LPG tank 125 includes a plurality of fill points 280, which enables the LPG tank 125 to be filled and the tank 125 associated equipment to be serviced. The LPG tank 125 provides gas to the burner 115. The fill points 280 may comprise a variety of fill points of different sizes and standards, and may include a vehicle LPG fill point, to enable the LPG tank to be filled at a petrol station, and a service point, to enable the LPG tank 125 to be serviced.

[00115] An air actuated (pneumatic) shut-off valve 285 is provided intermediate the tank 125 and the burner 115. The air actuated valve 285 is configured to close off the supply of gas from the tank 125 in response to air pressure provided by a pressurised air system of the tanker.

[00116] The pressurised air system may include a tanker brake system, wherein the pneumatic valve is only open when air pressure is applied to the brakes. Such configuration prevents the burner from operating unless the brakes are used, and thus prevents the burner from being engaged while the tanker 100 is in motion.

[00117] The tanker may include a fire safety element, configured to close a supply of fuel to the burner if a fire or bitumen spill is detected. The fire safety element may comprise plastic piping which is configured to melt if there is a fire or bitumen spill. The plastic piping may be configured to cut off an air supply to the pneumatic valve 285, thereby closing a supply of fuel to the burner, when melted.

[00118] The first safety element is advantageously positioned near a rear of the tanker 100, and is positioned such that a spill of hot bitumen would cause the piping to melt, thereby isolating the fuel. Similarly, should a fire break out near the rear of the vehicle, the piping would melt, isolating the fuel from the burner 115 in the same manner.

[00119] Alternatively, or additionally, other types of sensors may also be coupled to the valve 285, or otherwise be configured to shut off a supply of gas to the burner. Examples of such sensors include heat/smoke sensors, and/or other temperature sensitive materials.

[00120] The LPG, and the vaporised gas are monitored to ensure that excessive pressures are not created in the system. A venting arrangement is provided that ensures that in such circumstances, any gas is vented into a safe location. This design ensures that the components do not go above manufacturers maximum operating pressures.

[00121] An external gas supply path 290 is provided that includes a regulator 295, which is configured to provide gas at a predetermined pressure, and release gas through a quick connect coupling 300. This enables the operator to couple a manual burner to a gas supply in the tank 125, for example. The regulator 295 also includes a gauge, which enables the operator to monitor a pressure in the system between the tank 125 and the burner 115, and more particularly between the pneumatic valve 285 and the burner 115.

[00122] The tanker 100 further includes a solenoid valve 305, located on the tank 125, that is configured to close (i.e. prevent gas supply to the burner) should there be a loss of power to the tanker 100. As such, if there is an electrical fault, or power is otherwise disconnected to the tanker 100, the burner will stop. This is particularly useful if the tanker 100 includes electrical components, as it ensures that the burner does not continue to operate without power to these components.

[00123] The tanker 100 includes a plurality of hydrostatic relief valves 310, configured to provide a safe release of pressure and to protect the components and pipework in the event of excessive pressure in the pipework. Alternatively, or additionally, the tanker may include regulators and pressure safety valves (PSV) with partial or full relief for this purpose.

[00124] The tanker 100 further includes a plurality needle valves 315, to provide precise regulation of flow, and ball valves 320, to enable the operator to isolate various parts of the system. The ball valves may be located at different areas of the tanker 100, including adjacent to the tank 125, to enable a gas supply to be quickly shut off from a variety of areas.

[00125] While not illustrated, the tanker 100 may include a plurality of other sensors or control systems, which may be configured to cut off a supply of gas to the burner 115 when the system operates outside of certain operating parameters. As an illustrative example, the tanker 100 may include a bitumen over-temperature sensor and controller, that is configured to automatically shut off a supply of gas to the burner 115 when a temperature of the bitumen is outside of certain parameters. This may be achieved in a variety of ways, including being controlled via a thermostat that has an interrupter on the thermocouple 275.

[00126] Similarly, in addition to or instead of the thermocouple, other types of heat detectors (e.g. flame rod) or optical flame detectors (e.g. ultraviolet (UV), ultraviolet/infrared (UV/IR), multi spectrum infrared (MSIR) and visual flame imaging) may be used to determine the presence of a flame at the burner 115.

[00127] While the above description has primarily focused on LPG, other fuels may be used including butane, compressed natural gas (CNG), and liquefied natural gas (LNG). The fuel can be stored and/or provided in either liquid or vapour phase.

[00128] Similarly, instead of bitumen, the heating (immersion) tubes may be used to heat a variety of fluids, including water and tallow.

[00129] In alternative embodiments, the low-pressure path may be removed. While it is provided to deliver an appropriate quantity of fuel to the burner for lighting, alternative embodiments simply utilise a valve on the high-pressure path directly. Such configuration would require a trained and competent operator to light the burner. Further the configuration where the low pressure path is omitted may be suited to smaller systems on smaller bitumen tanks and therefore is not excluded from embodiments within the scope of this invention.

[00130] The tanker is illustrated above as a trailer. A variety of trailer types may be used, including dog trailers, semi-trailers, B-doubles and other combinations. The skilled addressee will readily appreciate that the tanker may take any suitable size and shape, and in one embodiment is provided directly on a truck chassis, rather than on a trailer. Similarly, the tanker may be static, and be configured to be supported by a frame directly on the ground, for example.

[00131] The tanker is illustrated in a transport configuration in Figure 1, but in alternative embodiments may include a sprayer, configured to spray the bitumen, e.g. directly onto a road surface. The tanker may be configured for transport only, for transport and spraying, or for spraying only.

[00132] Advantageously, the use of the low and high-pressure paths outlined above provided a burner that is easier and safer to light, and this can assist in preventing dangerous backfires. Such configuration does not require a flow of gas to be carefully controlled by the operator, but instead provides simple selection of "lighting" and "burning" configurations.

[00133] The use of a thermocouple and associated valve prevents the flow of gas to the burner when the burner is not lit. This in turn reduces the likelihood of dangerous levels of gas build up in the heating tubes or elsewhere. The thermocouple and valve do not require any external air or power supply to operate, and therefor provide a fail-safe system for shutting off gas flow.

[00134] The use of other sensors, valves and automatic shut off enable compliance with relevant safety standards, including all applicable Australian Standards.

[00135] The systems described above are less reliant on careful monitoring by operators, and are thus able to automatically respond to a variety of circumstances, e.g. by isolating a supply of gas.

[00136] Figure 8 illustrates a plan view of a burner 800 according to an embodiment of the present invention. Figure 9 illustrates an end view of the burner 800, Figure 10 illustrates a plan view of the burner 800 showing internal components in dashed lines, and Figure 11 illustrates an end view of the burner 800 showing the internal components in dashed lines.

[00137] The burner 800 is an atmospheric (venturi) burner particularly suited for use with a bitumen tanker, such as the tanker 100, but may also be used in other contexts, such as furnaces, or where an LPG burner may be required.

[00138] The burner 800 includes an outer tubular body 805, through which an inner tubular throat 810 extends. The outer tubular body 805 and the inner tubular throat 810 are coaxial and are joined by end plates 815 that extend between the outer tubular body 805 and the inner tubular throat 810, defining a chamber 820 therebetween.

[00139] The burner 800 includes an input 825, through which regulated LPG is provided in liquid form. The input 825 is tubular in shape and extends into the chamber 820 and is open in the chamber 820 adjacent to an outlet end of the burner 800, as best illustrated in Figure 10. The burner 800 further includes an output 830, which is also tubular in shape and extends into the chamber 820 and is open in the chamber 820 adjacent to an inlet end of the burner 800. The input 825 and output 830 are positioned on opposite sides of the burner 800.

[00140] In use, the output 830 is coupled to an injector 835 (nozzle), e.g. by a cooling coil or other pipework (not illustrated). The use of couplings (or fittings) on ends of the output 830 on the injector 835 enable the flexible coupling of intermediary elements, such as coils, intermediate the output and the nozzle. As an illustrative example, threaded fittings may be provided on ends of the output 830 on the injector 835 to simplify the process of coupling the burner 800 to pipework.

[00141] The injector 835 is provided adjacent to an opening of the throat 810 and is configured to inject vaporised LPG into the throat 810 to mix with air and be ignited. Inparticular, an inlet of the burner 800 comprises a venturi, where air (from the surrounding atmosphere) is induced, mixed with the vaporised LPG in the throat 810, and burnt at an outlet of the burner 800.

[00142] When the burner 800 is ignited, the flame heats the throat 810 and thereby the chamber 820. As the input 825 is open near the outlet of the burner 825, and the output 830 is open near the inlet of the burner 800 and on an opposite side to the input 825, the liquid LPG must travel along a length and width of the chamber 820, which provides uniform heating and vapourisation of the LPG.

[00143] The burner 800 may be formed of tubular steel and metal plates, which may be assembled and welded. The metal plates may be stamped and/or cut. Figure 12 illustrates an exploded view of components 1200 that may be joined to form a burner, such as the burner 800, according to an embodiment of the present invention.

[00144] The components comprise an outer steel pipe 1205, an inner steel pipe 1210, inlet and outlet end plates 1215, 1220, and inlet and outlet pipes 1225, 1230.

[00145] The outer steel pipe 1205 comprises 90NB (nominal bore) schedule 40 pipe, which is approximately 125mm long. The inner steel pipe 1210 comprises 50NB (nominal bore) schedule 40 pipe, which is approximately 180mm long.

[00146] The inlet and outlet end plates 1215, 1220 comprise annular stamped steel plates that are approximately 8mm thick, an outer diameter of the plates corresponding to the diameter of the outer steel pipe 1205 and the inner diameter of the plates corresponding to the diameter of the inner steel pipe 1210.

[00147] The inlet plate 1215 includes first and second apertures 1215a on opposite sides of the plate, through which the inlet and outlet pipes 1225, 1230 extend when in use. The inlet and outlet pipes 1225, 1230 comprise % inch steel tubing. The inlet pipe 1225 is longer than the outlet pipe 1230 as it extends further into the outer steel pipe 1205 (and the chamber defined between the outer steel pipe 1205 and the inner steel pipe 1210). In particular, the inlet pipe 1225 extends into the outer steel pipe 1205 approximately 105mm (i.e. until about 20mm from an end of the outer steel pipe 1205) and the outlet pipe 1230 extends into the outer steel pipe 1205 approximately 20mm. As a result, the ends of the inlet pipe 1225 and the outlet pipe 1230 are spaced apart by about 85mm.

[00148] In use, the components 1200 are welded together to form the burner. The components 1200 may be welded in any suitable manner, including a multi-pass gas tungsten arc welding (GTAW).

[00149] The various components 1200 may comprise stainless steel tubes and plates. Alternatively, the components 1200 may comprise cadmium coated steel tubes and plates. The components may be coated after assembly and welding.

[00150] By providing liquid LPG into a heating chamber near the front (outlet) of the burner, and receiving the vapourised LPG from the heating chamber near the rear (inlet) of the burner on an opposite side, the LPG is forced to travel both across the chamber, and along a length of the chamber prior to exiting the heating chamber. Such configuration provides greater consistency in pre-heating the LPG, and thus in the burner than having inputs and outputs near each other, as the LPG is forced to take a longer path through the chamber, thereby alleviating temperature spikes and dips.

[00151] The burners and systems described above may be manufactured to meet Australian Standard (AS) 1375-2013 Industrial Fuel Fired Appliances and AS 3814:2018 Industrial and Commercial Gas-fired Appliances.

[00152] The burners may be configured to operate at a maximum operating rating of 1,OOOMJ/hr, equivalent to 20kg of propane per hour, with a normal output of 300 - 600MJ/hour, equivalent to 6 - 12kg of propane per hour.

[00153] The burners may be configured to operate at a maximum operating pressure of 220kPa, and a minimum operating pressure of 7kPa (Low Fire requirement). Typical operating pressure may be between about 80 - 160kPa.

[00154] The burner may be configured to receive liquid LPG at around -42°C. The burner may be configured to provide vaporised LPG having a vapour temperature of between about 0C and about 80C. In a more preferred embodiment, the LPG vapour temperature may be between about 35°C and 70°C.

[00155] Vaporisation of the LPG, and an increase in temperature of the LPG, depends on the temperature of the heating chamber heating the LPG, and the time in which the LPG is in the heating chamber. It is believed that a spacing between the inlet pipe 1225 and the outlet pipe 1230 within the chamber (which is used to heat the LPG), which is between about 70mm and 90mm in a direction along an axis of the pipes sufficiently and effectively heats the LPG to temperatures to between 20°C and 70°C and effectively vaporises the LPG in a consistent manner.

[00156] The injector (nozzle) may comprise an aperture drilled to between about 2-3mm in diameter. The injector (nozzle) may be positioned between 148mm and 168mm from the outlet of the burner tube. The injector (nozzle) may comprise a "short pipe" nozzle with a coefficient of discharge (K) of around 0.82.

[00157] The systems may be configured to heat bitumen at a rate of no more than about 15°C per hour, and having a nominal bitumen heating rate of between around 8°C and 12°C per hour

[00158] The inventor has found that burners according to embodiments of the present invention, such as the burner 800, are able to operate in an efficient and consistent manner. Testing in the context of a bitumen tanker resulted in a heating rate of the bitumen of approximately 8- 10°C per hourwith an LPG consumption of approximately 350- 450MJ/hour. The LPG vapour temperature remained constant at around 40C. Flue gas analysis showed that the burner operated at an efficiency of around 95% with no measurable carbon monoxide produced and only 2% oxygen in the flue.

[00159] While the above burners have been described primarily in the context of bitumen tankers, the skilled addressee will readily appreciate that the burners may be used for any suitable purpose including in furnaces, heaters, kilns and the like.

[00160] In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises'and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers.

[00161] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[00162] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims (12)

CLAIMS:

1. A gas burner comprising a housing defining an elongate throat for receiving combustion gas and mixing the combustion gas with an oxidant, wherein an output of the burner is provided at an end of the throat; the housing further defining a pre-heating chamber extending along a length of the throat, the pre-heating chamber including an input, for receiving the combustion gas, and an output, for providing the combustion gas after it has been pre-heated, wherein the input and the output are spaced at least along a length of the pre-heating chamber, and wherein the pre-heating chamber is configured to pre-heat and/or vapourise the combustion gas prior to injection into the throat.

2. The gas burner of claim 1, wherein the pre-heating chamber extends around a periphery of the throat and the input of the pre-heating chamber is located on an opposite side of the chamber than the output.

3. The gas burner of claim 1 or claim 2, wherein the housing comprises an inner tubular body and an outer tubular body, wherein the pre-heating chamber is defined at least in part between the inner tubular body and the outer tubular body, wherein the throat is defined by the inner tubular body, wherein the throat is defined at least in part by an inside of the inner tubular body, and wherein the pre-heating chamber is defined at least in part by an outside of the inner tubular body.

4. The gas burner of any one of the preceding claims, wherein the burner comprises a nozzle, configured to inject combustion gas at or near the inlet of the throat under pressure, wherein the burner is configured to draw in air at the inlet of the throat when the combustion gas is injected into the throat, and wherein the output is configured to enable one or more intermediary elements to be coupled intermediate the output and the nozzle.

5. The gas burner of any one of the preceding claims, wherein the input and the output are spaced by at least half the length of the heating chamber.

6. A bitumen tanker, including a burner configured to heat bitumen in the tanker, wherein fuel is configured to be provided to the burner at a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, wherein the first predefined rate is lower than the second predefined rate.

7. A bitumen tanker, including a burner configured to heat bitumen in the tanker, the bitumen tanker including a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame of the burner goes out.

8. A fuel control system for a bitumen tanker, the bitumen tanker including a burner configured to heat bitumen in the tanker using the fuel, wherein the fuel control system is configured to provide fuel to the burner at a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, wherein the first predefined rate is lower than the second predefined rate.

9. A fuel control system for a bitumen tanker, the bitumen tanker including a burner configured to heat bitumen in the tanker using the fuel, wherein the fuel control system includes a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame of the burner goes out.

10. An immersion heating system including a burner configured to heat fluid in a reservoir by one or more immersion tubes, wherein fuel is configured to be provided to the burner at a first predefined rate for lighting the burner, and a second predefined rate for heating the bitumen, wherein the first predefined rate is lower than the second predefined rate.

11. An immersion heating system including a burner configured to heat fluid in a reservoir by one or more immersion tubes, the system including a flame failure valve, configured to automatically close a supply of fuel to the burner if a flame.

12. A bitumen tanker, including a gas burner as defined in any one of claims 1 to 5.