Patent Grant
9574771
Field of the Invention
Embodiments described herein generally relate to controlling the velocity of a gas flowing to a combustion chamber.
Description of the Related Art
Many industrial operations employ furnaces within which fuel and oxidant are combusted, so that the heat of combustion can heat material that is in the furnace. Examples include furnaces that heat solid material to melt it, such as smelting furnaces, and furnaces that heat objects such as steel slabs to raise the material's temperature (short of melting it) to facilitate shaping or other treatment of the material or object. The required high temperature is generally obtained by combustion of a hydrocarbon fuel such as natural gas. The combustion produces gaseous combustion products, also known as flue gas. Especially glass melting furnaces that achieve a relatively high efficiency of heat transfer from the combustion to the solid materials to be melted, the flue gases released generally reach temperatures in excess of 1300 degrees Celsius (° C.), and thus represent a considerable waste of energy that is generated in the high temperature operations, unless that heat energy can be at least partially recovered from the combustion products.
One mechanism to recover this lost energy is to preheat one or more of the combustion reactants (fuel or oxidant) using the flue gases. The combustion reactants can be heated to a desired temperature, thus increasing the heat delivered to the furnace during the combustion process. However, problems arise from the preheating of the combustion reactants. As the combustion reactants are heated in a given space, the pressure of the gases increases thereby leading to an increase in jet velocity exiting the burner. Jet velocity is the velocity with which the gases escape the burner. Increased jet velocity leads to shorter residence time before the combustion reaction which can reduce flame luminosity. A larger jet using a larger diameter of a pipe can resolve this problem, but this solution only creates a new problem when a lower reactant temperature is used. In other words, the velocity of the reactant decreases at the lower temperature in comparison to that of the reactant at the higher reactant temperatures.
Another way to overcome this problem is to use one pipe for the standard temperature fuel and another pipe for the hot fuel, with a valve switching the fuel flow between the two pipes. However, conventional valve designs used in the combustion art are complex devices that do not work well, or sometimes at all, at elevated temperatures. Further, conventional valves require manual operation (i.e. a person operating the valve based on temperature) which would require insulation and extra protection equipment for the operator. Also, insulating the valve requires even greater complexity and expense in order to ensure that the valve can perform in a routine fashion. Therefore, it is desirable for burners to have a function of automatic adjustment to maintain the proper jet velocity irrespective of the temperature change of the gas.
Thus, there is a need in the art for control of gas velocity exiting the burner during burner operations based on temperature.
The embodiments described herein generally relate to apparatus, systems and methods for controlling gas velocity exiting a burner. In one embodiment, a burner device can include a temperature-sensitive magnetic valve in fluid connection with a gas source and one or more first outlets in connection with a first pathway. The first outlets have a first cross-sectional area. The burner device also includes one or more second outlets in connection with a second pathway. The second outlets have a second cross-sectional area which is cumulatively greater than the first cross-sectional area. The temperature-sensitive magnetic valve can include a magnet, a ferromagnetic material in magnetic connection with the magnet and a flow control structure forming the first pathway and the second pathway.
In another embodiment, a burner system can include a temperature-sensitive magnetic valve having a magnet and a ferromagnetic material, a gas source coupled to the temperature-sensitive valve, a first burner outlet coupled to the temperature-sensitive magnetic valve and sized to permit gas at a first temperature to exit the first burner outlet at a first velocity and a second burner outlet coupled to the temperature-sensitive magnetic valve and sized to permit the gas at a second temperature to exit the second burner outlet at the first velocity, wherein the first burner outlet and the second burner outlet have different cross-sectional areas, and wherein the ferromagnetic material blocks the first burner outlet when magnetically coupled to the magnet and unblocks the first burner outlet when uncoupled from the magnet.
In another embodiment, a method for controlling combustion comprises delivering a gas at a first temperature to a temperature-sensitive valve, the temperature-sensitive valve comprising a magnetic material, a ferromagnetic material, a first pathway and a second pathway, wherein the gas exchanges heat with the ferromagnetic material such that the ferromagnetic material reaches the first temperature and is positioned at a first position relative to the magnetic material. The method also includes permitting the gas to flow through the first pathway that is coupled to the temperature-sensitive valve and delivering the gas at a second temperature to the temperature-sensitive valve, wherein the gas exchanges heat with the ferromagnetic material such that the ferromagnetic material reaches the second temperature. The method also includes moving the ferromagnetic material to a second position relative to the magnetic material that is different from the first position; and permitting the gas to flow through a second pathway that is coupled to the temperature-sensitive valve.
Any one or more of the embodiments may include one or more of the following aspects:
The flow control device has a plurality of first apertures and the ferromagnetic material is in fluid connection with the flow control device with plurality of second apertures formed therein.
The ferromagnetic material comprises a nickel-containing material.
The first pathway and the second pathway comprise one or more common pipes.
There is a chamber comprising a plurality of inlets and the ferromagnetic material further comprising an opening, the opening allowing substantial flow from the plurality of inlets into the chamber.
The first pathway and the second pathway comprise a pipe-in-pipe design.
The flow control structure is connected to the ferromagnetic material, wherein the flow control structure and the ferromagnetic material rotate on a pivot.
The temperature-sensitive magnetic valve further comprises a flow control structure configured to form one or more barriers to flow in conjunction with the ferromagnetic material.
The temperature-sensitive magnetic valve further comprises a restricting device configured to: change position with the ferromagnetic material; and redirect the gas based on the position of the ferromagnetic material in conjunction with the flow control structure.
There is a first flow control structure connected to the ferromagnetic material, the first flow control structure configured to restrict flow based on the temperature of the ferromagnetic material, wherein the flow control structure and the ferromagnetic material rotate on a pivot.
There is a second flow control structure with a plurality of apertures, the second flow control structure in fluid connection with the first flow control structure.
There is a chamber comprising the flow control structure positioned between a plurality of magnets, the flow control structure connected with the ferromagnetic material.
There is a protective cover configured to: isolate the ferromagnetic material or the magnet from the gas and transmit heat to at least the ferromagnetic material.
There is a first flow control structure connected to the ferromagnetic material, the first flow control structure configured to restrict flow based on the temperature of the ferromagnetic material, wherein the flow control structure and the ferromagnetic material rotate on a pivot.
The gas is either an oxidant or a fuel.
The ferromagnetic material comprises nickel.
The first pathway further comprises one or more first outlets.
The second pathway has one or more second outlets which have a cumulative cross-sectional area which is greater than the first pathway.
If and when the temperature-sensitive valve fails, placing a magnet in a position sufficient to induce the ferromagnetic material to either the first position or the second position.
The first temperature is the prevailing ambient temperature and the second temperature is a predetermined temperature to which the gas has been preheated prior to said step of delivering the gas at a second temperature.
The gas is a fuel.
The gas is natural gas.
The gas is preheated to the second temperature through heat exchange with hot air that has been preheated through heat exchange with combustion gases resulting from combustion of gas injected by the burner
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
Burners, apparatuses, systems, and methods for controlling gas velocity exiting through an outlet in a burner are disclosed herein. Significant energy is lost during the combustion process, specifically through heat that escapes to the atmosphere in flue gases. For example, in an oxy-fuel fired glass furnace where all the fuel is combusted with pure oxygen, and for which the temperature of the flue gas at the furnace exhaust is of the order of 1350° C., typically 30% to 40% of the energy released by the combustion of the fuel is lost in the flue gas. In embodiments described herein, a gas, such as gaseous fuel or oxidant, can be preheated prior to delivery to a combustion chamber through an outlet in a burner. The flow of the gas, whether preheated or standard temperature, can be redirected using a temperature-sensitive magnetic valve through one or more pathways. The gas can then be delivered via one of the pathways to the combustion chamber by exiting through one or more outlets. The outlets, either individually or as a group, can have a cross-sectional area which allows for a substantially constant velocity of gas exiting the outlets of the burner for operation involving two predetermined temperature ranges for the gas. The embodiments disclosed herein are more clearly described with reference to the figures below.
As discussed above, the temperature-sensitive magnetic valve operates to ensure that the velocity of the gas exiting the burner remains substantially the same, whether the gas is preheated to a pre-selected temperature range or not. For simplicity, the ideal gas law will be used to explain how a substantially constant velocity is maintained. As is well known, the ideal gas law states that the product of the pressure of a gas and the volume of the gas equals the product of the moles of the gas, the temperature of the gas, and the universal gas constant (i.e., PV=nRT). If the temperature changes (e.g., the gas delivered to the valve increases), then the volume of the gas increases if pressure is held constant. Thus, gas passing through the same outlet at different temperatures will have a velocity due to the different volume. To ensure that different temperature gases exit the burner at the same velocity, the increase in volume (due to the increase in temperature), must be accounted for. To account for the increase in volume, the gas at the higher temperature may be directed to a different outlet that is sized to permit the gas to exit the different outlet at substantially the same velocity as the gas at the lower temperature exits the original outlet. Because the velocity of the jet of gas remains the same, whether the gas is at the first temperature or at the second temperature, the flame resulting from combustion of the gas jet (with another combustion reactant) will have a same size and shape. This solves the problem associated with changes in flame size and shape that are experienced by conventional burners operated in heated gas or non-heated gas modes.
In the embodiments discussed herein, the gases may be delivered within a temperature range of between about 25 degrees Celsius and about 800 degrees Celsius. Additionally, in the embodiments discussed herein, the ferromagnetic material may be chosen to have a curie temperature between about 240 degrees Celsius and about 600 degrees Celsius. In general, the desired temperature to which the gas is preheated, the typical non-preheated gas temperature, and the desired jet velocity (of the gas exiting the outlet) drive selection of the cumulative cross-sectional areas for the first and second flow paths and drive selection of the particular temperature selective magnet.
Take, for example, a first flow path for non-preheated gas and a second flow path for preheated gas where the typical non-preheated temperature is ambient (25° C. or 298° K), the desired jet velocity is 100 m/s, and the desired preheated gas temperature is 480° C. (753° K). In this case, the temperature has increased by about 53%, so the cross-sectional area for the second flow path should be about 53% greater than that of the first flow path plus the material for the temperature selective magnet is chosen so as to exhibit the curie effect at a temperature lower than 480° C. This will help to ensure that the jet velocity will be substantially the same whether the gas temperature is ambient or 480° C. One of ordinary skill in the art will recognize that selection of the first and second gas temperatures is only limited by the availability of materials exhibiting the curie effect at temperatures in between the first and second gas temperatures. Such a one will further recognize that the first and second gas temperatures are typically driven by process requirements.
While two flow paths and two operating temperatures are disclosed, it is within the scope of the invention to utilize three or more flow paths corresponding to three or more operating temperatures. The ultimate number of flow paths is only limited by the tradeoff between expense and complexity of such a device and the desirability of having a substantially constant jet velocity at each of the different operating temperatures.
While the invention may be used in any of a wide variety of combustion processes, one typical process is a glass furnace where either the oxidant (such as air, oxygen-enriched air or oxygen) and/or the fuel is preheated at a heat exchanger with heat from either combustion gases from the furnace or with heat from air that is itself preheated from heat from the combustion gases. The first temperature corresponds to a first mode of operation in which the oxidant and/or the fuel is not preheated at the heat exchanger. The second temperature corresponds to a second mode of operation in which the oxidant and/or the fuel is preheated at the heat exchanger.
The first gas 103, shown in
The temperature-sensitive magnetic valve 104 can have a plurality of states. The temperature-sensitive magnetic valve 104 has a first state and a second state, such that gas flows through the first tube 106 when in the first state and the gas flows through the second tube 108 when in the second state. The temperature-sensitive magnetic valve 104 includes at least a magnet and a ferromagnetic material. When in the first state, the ferromagnetic material is magnetically coupled to the magnet. When the temperature of the ferromagnetic material increases, the ferromagnetic material loses its magnetic properties and thus magnetically decoupled from the magnet. The magnetic decoupling occurs because the ferromagnetic material reaches a curie effect temperature and loses attraction to the magnet. Once the ferromagnetic material reaches the curie effect temperature, the ferromagnetic material moves away from the magnetic and, thus, the valve shifts to a second state. In the first state (shown in
As discussed above, then the ferromagnetic material reaches the curie effect temperature for the particular ferromagnetic material, the ferromagnetic material magnetically decouples from the magnet and thus, physically moves away from the magnet. Due to the movement of the ferromagnetic material, the valve 104 operates to alter the flowpath of the gas passing through the valve. As shown in
When the temperature-sensitive magnetic valve 104 shifts from the first state to the second state, the flow of gas is shifted from the first tube 106 (the first pathway) to the second tube 108 (the second pathway). The second tube 108 leads through the burner block 110 to the second outlet 114. The second outlet 112 has a cross-sectional area that is different than the cross-sectional area of the first outlet 112. Because the cross-sectional area of the first outlet is appropriately selected to correspond with the predominant temperature of the first state (such as the prevailing ambient temperature) and the cross-sectional area of the second outlet is appropriately selected to correspond with the predominant temperature of the second state (such as 480° C.), the exiting gas 118 exits the second outlet 114 at the same velocity as the gas exiting the first outlet 112. Though depicted in
Therefore, so long as the cross-sectional area of the outlet associated with the second flow path is sized to achieve a particular jet velocity at a second desired gas temperature and the cross-sectional area of the outlet associated with the first flow path is sized to achieve a same jet velocity at a first desired gas temperature, by using the temperature-sensitive magnetic valve, the jet velocity of the gas exiting the burner is the same whether the gas is at the first or second temperature.
As shown in
Though shown here as permutations of a dual pipe embodiment, various designs may be employed to control velocity of gases delivered through the outlets. In general, the designs for both the valves and the pipes are only limited by the desire to maintain the same gas velocity when delivering either heated or standard temperature gases through an outlet in a burner.
Embodiments described herein relate to relevant portions of a typical burner useable with one or more embodiments of the invention. There can be other components that are not explicitly named which may be included or excluded based on the choice of design and other parameters. The components described herein may differ in shape, size or positioning from those used in practice. Further, the embodiments described herein are for exemplary purposes and should not be read as limiting of the scope of the invention described herein, unless explicitly limited herein.
In this embodiment, a magnet 318, a ferromagnetic material 316, a flow control structure 314 and a plurality of ports 315 are shown without a valve chamber, for clarity. The valve chamber is more clearly described with reference to
The magnet 318 can be positioned in proximity of the ferromagnetic material 316. The magnet 318 can be of a standard composition for a high temperature magnet, such an AlNiCo magnet. Though shown here as connected with the flow control structure 314, the magnet 318 can be positioned either internal, external or as part of the flow control structure 314. Further, the magnet 318 can be an electromagnet or a permanent magnet. In embodiments described here, the magnet 318 is shown as a permanent magnet.
The ferromagnetic material 316 is a ferromagnetic material which becomes paramagnetic at a specific temperature, known as the curie-effect temperature. The curie-effect temperature of a substance is dependent upon the composition of the substance. In one or more embodiments, the ferromagnetic material 316 is primarily nickel, which has a curie-effect temperature of 358° C. In one embodiment, the ferromagnetic material 316 is a nickel alloy which contains more than 95% nickel, such as nickel alloy 200. The ferromagnetic material 316 can be of any composition which has a curie-effect temperature in the desired range.
The ferromagnetic material 316 as positioned with the flow control structure 314, creates a plurality of ports 315 for gas to flow through, shown here as twelve (12) open ports 315 of approximately equal size. Though a specific number and similar approximate size of the ports 315 is shown in this embodiment, it will be appreciated by one skilled in the art that the number and size of ports 315 available can be changed. In either state of the temperature-sensitive magnetic valve 300, the port size, number and organization can be altered and adjusted based on the needs or desires of the user. The ports 315 need not be positioned uniformly nor be of the same size.
As gas flows through the temperature-sensitive magnetic valve 300, the ferromagnetic material 316 equilibrates to the temperature of the gas, as shown in
Embodiments herein generally rely on one or more sources of force to actuate between the first state and the second state, shown here as the spring 312. When the ferromagnetic material 316 reaches the curie-effect temperature, the magnet 318, which acts as the first source of force, no longer holds the ferromagnetic material 316 in place. The second source of force, in the absence of the first source of force, moves the ferromagnetic material 316 and the flow control structure 314 to a second state. Examples of the second source of force can include springs, gravity, pressure (such as dynamic or differential static pressures) or even additional magnets (such as magnets acting on a different section, a different material e.g. carbon steel, or with a different strength).
Without intending to be bound by theory, most simple designs utilize actuation that moves a single component only a few millimeters due to the limited range of the magnetic field. As such, several magnets can be “cascaded” to increase the range of movement. Advantageously, it is believed to be possible to move the actuator a much greater distance using cascaded magnets. A ferromagnetic material can only travel a certain distance relative to a fixed magnet. Thus, by using more than one magnet with at least one intermediate magnet which is not stationary, the overall travel distance can be increased. Further, the valve could be gradually closed using a multiple magnet design. If oriented properly or composed of ferromagnetic materials with separate curie-effect temperatures, the individual ferromagnetic materials used for actuation would reach the threshold temperature at different rates. This is believed to create a time delay between when the preheated gas is delivered and when the ferromagnetic material actually heats up sufficiently. The time delay can be based on convective heat transfer which itself depends on material properties and flow dynamics/geometry (which can be altered between components to achieve different delays). One skilled in the art will understand that there are various permutations of the cascading design which can be employed without diverging from the invention described herein. Possible designs include any design which maintains the same gas velocity between heated and standard temperature gases delivered through outlets in the burner.
Positioned inside of the temperature-sensitive magnetic valve 400 is a ferromagnetic material 422 that is magnetically connected with a magnet 420. In this embodiment, the magnet 420 is stationary. The ferromagnetic material 422, shown in
In
The heated state, or second state, is shown in
The ferromagnetic material 534a and the flow control structure 534b can be composed of the same material or separate materials. As only the ferromagnetic material 534a needs to be composed of a temperature-sensitive substance, the composition of the flow control structure 534b beyond pivot 537 can be different from the ferromagnetic material 534a before pivot 537, as measured from the magnet 536. For example, the composition of flow control structure 534b beyond an imaginary line 539 can be a material which is more or less dense than the composition of ferromagnetic material 534a. The imaginary line 539 need not be positioned at the pivot 537 and the separation between the ferromagnetic material 534a and the flow control structure 534b can be at any point along the combination.
One or more embodiments can employ rotating components or be adapted to use rotating components, as shown in the exemplary embodiment of
When a second, higher temperature gas flows into the valve chamber, the ferromagnetic material 640 can begin to heat up, described with reference to
When a higher temperature gas flows into the valve chamber 750, shown in
As stated with reference to other embodiments, ferromagnetic materials 754a and 754b may be of the same composition as one another, the same composition as the restricting device 756 or of different compositions based on the needs of the user. The imaginary lines 755a and 755b are positioned for exemplary purposes and the imaginary lines 755a and 755b between the ferromagnetic materials 754a and 754b and the restricting device 756 may be more or fewer than two, may be in different positions than shown or may not exist, in one or more embodiments.
When a preheated gas flows into the valve chamber 860 described with reference to
The protective cover 865 is positioned to allow the magnetic field of the magnet 864 to be delivered to the ferromagnetic material 866, while protecting the magnet 864 from the gas delivered to the valve chamber 861. The protective cover 865 can be formed of a ferromagnetic material which does not degrade in the operative environment, such as nickel or Inconel. Further, the protective cover may be a magnet itself, such as a cobalt containing magnet. The protective cover can allow stronger magnets which are not optimal for the conditions of the tube, for example magnets which are sensitive to temperatures or gases, to be used in the temperature-sensitive magnetic valve 800.
Insulation may also be used to isolate the magnet 864, in one or more embodiments described above, from the high temperatures or certain chemistries of gases delivered through the burner to the combustion chamber. For example, a very thin vacuum insulated housing may protect the magnet 864 from excess heat. Passive or active convective/conductive cooling may be utilized to keep the magnet cool, relying on other cooler process flows in the vicinity of the magnet 864. Of note, most magnets of useful size only have a field that will attract objects within a few millimeters. Thus, the amount and type of insulation used should take account of the limited range for these magnets. The insulation used to isolate the magnet 864 can be less than 10 mm.
Most designs are depicted with one magnet for simplicity purposes only. Other designs may include one or more magnets, in one or more positioning and orientations based on the needs of the user and the design of the valve, without diverging from the scope of the invention described herein. In one embodiment, additional magnets 864 could be employed for increasing the overall field strength, such as magnets oriented to create a field in the same direction, whether in series or in parallel. In another embodiment, additional magnets can be employed to achieve a more complex motion of the actuated pieces, such as magnets aligned perpendicularly to allow for a two-step series of motion below the curie-effect temperature. In another embodiment, additional magnets can be “staged” in such a way that they actuate at slightly different times due to different heating rates. In another embodiment, additional magnets and additional ferromagnetic materials can be staged so as to increase the distance travelled.
The method 900 begins at step 902 by delivering a first gas at a first temperature to a temperature-sensitive valve, the temperature-sensitive valve comprising a magnetic material, a ferromagnetic material, a first pathway and a second pathway. The gas exchanges heat with the ferromagnetic material such that the ferromagnetic material reaches the first temperature, which can be below the curie-effect temperature for the ferromagnetic material. As the gases flow into the temperature-sensitive valve, the components which are in thermal contact with the gas equilibrate based on the first temperature of the gas and the starting temperature of the components of the temperature-sensitive valve. As the gases are delivered to the temperature-sensitive magnetic valve, the components of the temperature-sensitive magnetic valve including the ferromagnetic material will change from the starting temperature to the first temperature. If the ferromagnetic material is spaced from the magnet, then, as the ferromagnetic material lowers to below the curie-effect temperature for the particular ferromagnetic material, the ferromagnetic material will become magnetically coupled to the magnet and move into the first position.
In this embodiment, the first gas exchanges heat with the ferromagnetic material such that the ferromagnetic material reaches the first temperature and is positioned at a first position relative to the magnetic material. The first position fluidly connects the gas source with the first pathway. As described above, the ferromagnetic material can be magnetically connected with the magnet when at the first temperature. Thus the magnet holds the ferromagnetic material in a first position which allows flow through the valve and through the first pathway. While the ferromagnetic material is in the first position, access to the second pathway through the temperature-sensitive magnetic valve is closed.
The terms “first pathway” and “second pathway” as used both here and above refer to the fluid connections (e.g., pipes or tubes) which are open when the temperature-sensitive magnetic valve is in the first state and second state respectively. In one or more embodiments, the first pathway and the second pathway have one or more common fluid connections. In one embodiment, the first pathway includes a first pipe and a second pipe and the second pathway includes the first pipe, the second pipe and a third pipe.
Then a second gas is delivered at a second temperature to the temperature sensitive valve, as in step 904. After equilibrating the temperature of the first gas and the temperature-sensitive magnetic valve, a second gas may be delivered to the temperature sensitive magnetic valve where the second gas is at a second temperature. The second temperature can be above the curie-effect temperature for the particular ferromagnetic material. The second gas then exchanges heat with the ferromagnetic material such that the ferromagnetic material reaches the second temperature.
The ferromagnetic material is then moved to a second position relative to the magnetic material that is different from the first position, as in step 906. As described above, once the ferromagnetic material transitions across the curie-effect temperature boundary, the interaction between the magnet and the ferromagnetic material is affected, creating a shift in position. In one embodiment, the ferromagnetic material temperature increases and thus, meets and then exceeds the curie-effect temperature. Therefore, the ferromagnetic material decouples from the magnet and moves to the second state. A second force, such as a spring or gravity can overcome the weak magnetic attraction between the magnet and the ferromagnetic material at a temperature above the curie-effect temperature thus shifting the temperature sensitive magnetic valve from the first state to the second state. In another embodiment, the second temperature can be lower than the first temperature such that once the ferromagnetic material reaches the second temperature, the ferromagnetic material is below the curie-effect temperature. Thus, the magnetic material can then exert magnetic force to move the ferromagnetic material to the second position.
The transfer of heat to the ferromagnetic material does not need to be a direct transfer. In one or more embodiments, an insulated heat pipe could sample and “transmit” heat from the area where process flow temperature is seen, to the ferromagnetic material positioned proximate, but thermally isolated from, the gas, such that the ferromagnetic material is not directly subject to the heat or chemistry of the gas. The ferromagnetic material loses magnetic attraction based on the temperature change. A mechanical connection can then transmit the action of the ferromagnetic material back to the restricting device and the flow control structure to redirect the process flow.
The second gas is then permitted to flow through a second pathway that is coupled to the temperature sensitive valve, as in step 908. After the temperature sensitive valve shifts from the first position to the second position, the second pathway is opened. The second pathway can incorporate none of, portions of or the entirety of the first pathway. The second gas is delivered through the second pathway and flows through a second outlet in the burner to the combustion chamber, such that the velocity of the gas exiting the first outlet is substantially the same as the velocity of the gas exiting the second outlet.
Regardless of which path the temperature-sensitive magnetic valve directs the gas, the gas will exit the burner at substantially the same jet velocity regardless of the temperature of the gas.
In case the temperature-sensitive magnetic valve malfunctions and the ferromagnetic feature cannot be moved toward or away from the magnet (as the case may be), movement towards or away from can be forced by judicious placement of a strong magnet so as to move the ferromagnetic feature in the desired direction. This strong magnet may be applied to an outside surface of the valve (or apparatus incorporating the valve) so that an operator may manually provide a back-up solution in case the inventive valve fails.
Embodiments described herein relate to control of gas velocity exiting a burner. Recovery of lost thermal energy is becoming more important as fuel costs rise. One important source of lost thermal energy in standard furnaces is through flue gas. This lost thermal energy can be recovered through heating of the combustion gases prior to combustion. Heating the gases however can change the velocity of the gases as delivered through the outlet of the burner to the combustion chamber. By redirecting the flow based on a threshold temperature, combustion gases can exit the burner at a constant velocity regardless of the temperature of the gases.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
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