Waste fluids such as waste oil can include a combination of hydrocarbons, oils, gasses, water, other liquids and solids obtained naturally or as a residue from processing. Because oil and other base materials of waste fluids are so viscous, waste fluids can be diluted with additives that become part of the combination so that it can be processed or transported by pipelines and tank cars. The recovery of valuable portions of waste fluids requires extraction and separation systems to separate the various components of the waste fluid.
Aspects of the present disclosure can be better understood with reference to the following drawings. It is noted that the elements in the drawings are not necessarily to scale, with emphasis instead being placed upon clearly illustrating the principles of the embodiments. In the drawings, like reference numerals designate like or corresponding, but not necessarily the same, elements throughout the several views.
As noted above, waste fluids can include a combination of hydrocarbons, oils, gasses, water, other liquids and solids obtained naturally or as a residue from processing. The present disclosure describes inductive heaters for fluids. The inductive heaters described herein can help processing and transportation of these fluids, and in some cases can help extract valuable or useful materials from these fluids. The device can receive colder fluid at one end and emits hotter fluid at the other.
In some embodiments, the inductive heater uses magnetic induction as the primary source for heating although supplemental heating is contemplated, such as a pre-heater. Some of these pre-heaters can use excess heat from inductive coils to pre-heat fluids such as waste oil before this fluid enters the inductively heated portion.
In some embodiments, the inductive heater includes an inductively heated manifold assembly. Liquid comes in one end and is diverted into smaller pipes of the inductively heated manifold assembly, heated, and recombined at the end of the manifold assembly. Also, an inductively heated serpentine assembly can be used. In some embodiments, the serpentine assembly can include straight inductively heated sections, which can include an inductively heated pipe and/or an inductively heated manifold assembly that is divided into multiple pipes as discussed.
In some cases, the inductive heaters can use frequency of a power source (e.g., a generator or utility power) as the frequency emitted by the inductive heater. This frequency can be as line frequency or utility frequency (e.g., 50 Hz, 60 Hz, 140 Hz, 400 Hz, etc.). In some embodiments, lower frequencies can penetrate the pipes, vessels or conduits of a heater assembly deeper than higher frequencies. Frequency can be chosen or designed to match the requirements of the application, including power source, and heater assembly
Moving now to the figures,
In some cases, the effective heating distance of the inductive coil 112 can be designed to be a predetermined percentage of the diameter of the inductive coil 112, for example, approximately 5% of the diameter of the inductive coil 112, or approximately 50% of the diameter of the inductive coil 112. The effective heating distance of the inductive coil 112 can be designed to be other percentages of the diameter of one of the manifold pipes 115, from 0% to 200% are contemplated. In other cases, the effective heating distance of the inductive coil 112 can be designed to be a predetermined percentage of a diameter of one of the manifold pipes 115, for example, inductive coil 112, for example, approximately 50% of the diameter of one of the manifold pipes 115, or approximately 100% of the diameter of one of the manifold pipes 115. The effective heating distance of the inductive coil 112 can be designed to be other percentages of the diameter of one of the manifold pipes 115, and any percentage can be contemplated, depending on the particular diameter of the manifold pipes 115. As discussed earlier, lower frequencies can penetrate the pipes, vessels or conduits of a heater assembly deeper than higher frequencies. Frequency can be chosen or designed to match the requirements of the application, including power source, and heater assembly arrangement.
Each of the manifold pipes 115 can be smaller than the entrance pipe 104. The inductively heated manifold assembly 103 can include any number of manifold pipes 115. In some embodiments, the manifold pipes 115 can be arranged such that they fit within a circle having a diameter similar to an external diameter of the entrance pipe 104, or a circle having a diameter that is the same as the external diameter of the entrance pipe 104. Where the entrance pipe 104 is inductively heated using an inductive coil of a certain diameter, it can be beneficial for the inductive coil 112 around the manifold pipes 115 as a whole to use a similar diameter. This can aid simplicity of design and compatibility of parts.
In some cases, each of the manifold pipes 115 can be the same size, such that one of the manifold pipes 115 has a same diameter as another one of the manifold pipes 115. In some cases, the manifold pipes 115 can be arranged or designed such that multiple different diameters are used. Further, the manifold pipes 115 can be arranged within a circular cross-sectional area that is approximately an inside diameter of the inductive coil 112 using a circle packing or a circle packing technique that can be used to specify that each of the manifold pipes 115 touch one another, or such that each of the manifold pipes 115 are within a certain maximum distance from one another, or within a certain minimum distance from one another, while a subset of the manifold pipes 115 (e.g., those towards the outside of the bundle) maintain a certain minimum (or maximum) distance from the inductive coil 112 that is around the manifold pipes 115. The inductive coil 112 can be a helical coil. The coil configuration in can be calculated to match a generator or power source and can be designed so that the desired heat rise or delta is achieved in the inductive heater as a whole, and/or in the inductively heated manifold assembly. If more heat is required the length of the inductively heated manifold assembly 103 can be extended straight, serpentine, or in other configurations as is suitable to the space allocated to provide the desired heating.
In some cases, the manifold pipes 115 can be designed so that a sum of the internal cross-sectional areas of the manifold pipes 115 is similar to (e.g., up to 25% greater or lesser) a cross-sectional area of the entrance pipe 104. In some cases, the manifold pipes can fit within a circle of a diameter greater than the external diameter of the entrance pipe 104. Also, since the pipes themselves take up a certain amount of area, the sum of the internal cross-sectional areas of the manifold pipes 115 can be less than the entrance pipe 104 where the manifold pipes 115 fit within a circle having a diameter similar to the external diameter of the entrance pipe 104. In some cases the inductively heated manifold assembly 103 and the inductive coil 112 can be encased in an enclosure or housing (not shown). The housing can include air, water, argon or another inert gas, or another heat exchange fluid, and can be in fluid connection with a pre-heater in a heat exchanging system to exchange heat and pre-heat the entrance pipe 104 and thereby pre-heat the waste oil or other fluid to be heated.
In some examples, the inductively heated serpentine assembly 200 can include an inductive coil around each of the straight sections 209 with inductive coils 211. The elbow sections 212, for assembly purposes and/or service access, may not be surrounded by an inductive coil as shown. However, in some cases, one or more of the elbow sections 212 can be surrounded by an inductive coil.
In some cases, the entrance 203 can be higher than the exit 206 so that gravity can assist the aggregate flow of fluid in the fluid system of the inductively heated serpentine assembly 200, as shown. In some cases, the inductively heated serpentine assembly 200 can be designed to have a downhill design or drain slope. To this end, each straight section 209 of the inductively heated serpentine assembly 200 can maintain a drain slope. Each successive straight section 209 can be lower than the previous section such that the drain slope is maintained such that the inductively heated serpentine assembly 200 has a downhill flow and the fluid being heated does not have to flow uphill within the serpentine assembly 200. For example, the serpentine assembly 200 can have a top row of straight sections 209, and a lower row of straight sections. The fluid can flow through each of the a top row of straight sections 209 before moving or flowing to the next, lower row of straight sections, and so on to the exit 206. In some examples, the inductively heated serpentine assembly 200 can further be driven by a pump. In some cases, the pump can provide sufficient pressure such that slope considerations are unnecessary.
In some cases the inductively heated serpentine assembly 200 can be encased in an enclosure or housing (not shown). This enclosure can utilize excess heat from the system, such as heat that is generated outside of the pipes containing waste oil or other fluid to be heated. The excess heat can be utilized in a heat exchanging system. The heat exchange system can include a pre heater for the waste oil or other fluid being heated, as will be discussed. The enclosure or housing can include air, water, or another heat exchange fluid, and can be in fluid connection with a pre-heater in a heat exchanging system to exchange heat and pre-heat, for example, an entrance pipe and thereby pre-heat the waste oil or other fluid to be heated.
In some cases, there can be a center manifold pipe (corresponding to the manifold pipe connector 318), and the rest of the manifold pipes can be arranged, for example in a circular pattern, around the center manifold pipe as shown (i.e., outer manifold pipes). The outer manifold pipes can each have the same diameter or approximately the same diameter. The center manifold pipe can have a same diameter as the outer manifold pipes, a larger diameter than the outer manifold pipes, or a smaller diameter than the outer manifold pipes in the various embodiments. In other cases, the manifold pipes 115 can be arranged in a circular pattern around a center area occupied by a magnetic flux shield material or a high permeability material to affect the magnetic field of the inductive heater and increase heating of the manifold pipes. For example, a center hollow pipe or solid pipe that comprises magnetic flux shield material or a high permeability material. The center manifold pipe can also be injected with hot oil, gas, or other fluid.
In order to increase inductive coupling, in some cases, the center manifold pipe can be wrapped or surrounded by another inductive coil around the center manifold pipe. The other inductive coil around the center manifold pipe can heat the center manifold pipe as well as help to heat the outer manifold pipes arranged around it.
In
Induction Heater Design:
The induction coils can include several runs or sections of inductively heated pipes and or manifold assemblies, an inlet waste oil header, an outlet waster oil header, and multiple coiling cooling flow headers. The heat can be generated within the pipe wall. A coil can be made of the flat copper coil or copper tubing. Where a pre-heater 403 is used, water or other fluid can be included in an enclosure about the induction heater 406, and an internal flow of the heated fluid can be provided from the induction heater 406 into a the pre-heater 403 and cool fluid can re-enter the enclosure of the induction heater 406. For inductively heated sections, any magnetically or electrically conductive materials such as carbon steel, aluminum, and stainless steel could be considered, including pipes, tanks, and manifold assemblies of pipes. The heat transfer can be simplified as constant heat flux on the interface of the wall of the pipes to the fluid to be heated. The maximum heat flux could be applied to the waste oil is limited by the convective heat transfer rate inside the pipes. The various embodiments include vessels and pipes or other containers made of. In one embodiment an upright tank's liquid can be heated with inductive coils that surround the tank, or pancake coils that are mounted with the coil flat to the side of the tank.
In some examples, the fluid can include waste oil described as follows:
Fluid: waste oil (approximately 50% water, 50% oil)
Inlet temperature Ti: 50 F (12° C.)
Outlet target temperature To: 180 F (82° C.)
Fluid properties at mean temperature Tm=(Ti+To)/2=47° C. The thermo-physical properties of the waste oil is weighted according to its composition.
Density ρ=(873+989)/2=931 kg/m3
Specific heat cp=(1.76+4.06)/2=2.91 kJ/kg/K
Dynamic viscosity v=(6e−7+3e−6)/2=1.5e−6
Thermal conductivity k=(0.6+0.12)/2=0.36 W/m/K
Prandtl number Pr=1.5e−6/(0.36/2910/931)=11
In one example, the flow rate can be 50 GPM (0.0032 m3/s). The desired temperature rise can be 130° F.
Total heating power required
Qh=ρGcp(To−Ti)=0.6 MW
Total power source power, assuming 60% overall electrical to heat efficiency ηt without heat recovery:
Total power source power, assuming 60% overall electrical to heat efficiency ηt with heat recovery of recovery efficiency ηr of 80%:
System Configuration:
For initial sizing in this embodiment, we consider a pipe diameter D of 2 inches. In the example of a serpentine or any other arrangement of pipe sections of length (L) of inductively heated pipes, a combination of diameter (D), and section length (L), and number of sections can be determined. In the example of a serpentine arrangement, a number of sections (S) can be M×N, where N is a number of rows and M is number of columns. As an example, we can set N=4 and M=5.
The flow rate in each serpentine pipe can be G/N. The Reynolds number can be 13367 in the fully developed turbulent region.
The Nusselt number can be
NuD=0.023ReD4/5Pr0.4=119
The convective heat transfer coefficient can be
The minimum temperature difference between the fluid and the pipe wall would occur at the outlet, where the fluid temperature equals to the target temperature of 82° C. Assuming the boiling point of the waste oil is 176° C. (350 F), which is the limiting wall temperature, then the minimum heat flux would be
qmin=hconv(176−82)=77112 W/m2
At the inlet, the allowable or maximum heat flux can be greater
qmax=hconv(176−12)=137088 W/m2
For the actual system, each group of the coils can be controlled independently to achieve maximum performance. For the initial sizing, we can consider constant heat flux throughout the full pipe length of qm=qmax+qmin)/2=107.1 kW/m2.
The heat delivered to the induction heater can be
Qinduction=Qp×ηt=0.39 MW
Which can also be calculated as
Qinduction=πDLMNqm
Therefore, in this example, for M=5, L=1.14 m. The total footprint of this embodiment of the induction heater itself would be less than 2 by 2 by 2 m (or less than 6 ft by 6 ft by 6 ft).
The pressure drop through the heater, the induction coil assembly efficiency (e.g. number of turns) are not considered in this preliminary heat transfer analysis. A full design optimization can consider a balance between the cost and effectiveness of all three aspects of the system including heat transfer, pumping, and electrical.
The power source can be utility power. However, other energy sources in other embodiments may be used (e.g., an electrical generator or fuel cell). When practical the natural frequency of the line can be utilized, although it may be factored or multiplied in some embodiments. For example, line frequency of 60 hertz may be factored to 120 hertz or 240 hertz as the engineering finds expedient. While low frequencies (e.g., utility frequencies like 50 Hz, 60 Hz, 140 Hz, 400 Hz are contemplated for most embodiments, higher frequencies may be utilized as desired for the application.
The transformer 512 may not be necessary in some embodiments if the line power is clean and appropriate for direct use. The relays and breakers or fuses 515 can allow for soft switching by initial use of lower current and/or voltage and once the connection is made, increasing current and/or voltage.
The impedance matching network 518 can provide for good energy transfer, and can be adjusted by the controller 530 in view of the inductive coils 524. In some embodiments like in line fluid heating as in
In some embodiments, but not all embodiments, insulation can be used to regulate temperature and heat escaping the pipes. In some embodiments, heating waste oil inline, the heat generated by the coils and power supply can be captured by the heat exchange fluid that is inside the enclosure that can surround the coils, as well as the power unit. The heat exchange fluid can be water or other liquids, air or other gasses, or another fluid. The heat exchange fluid can be routed through pre-heater in a heat exchange arrangement to capture the heat and preheat the waste oil or other fluids before they enter the inductively heated sections. Tank embodiments can use pancake coils radially mounted to the sides or helical surrounding coils.
As used herein, the term “approximate,” or “approximately” can refer to a distance or measure that differs by about 30% or less, about 25% or less, about 20% or less, about 15% or less, about 10% or less, or about 5% or less than the indicated distance or measure. The term “or less” can indicate a range that extends to 0% or to 0.01%. As used herein, the term “similar to,” for example in the phrase “diameter similar to,” can refer to diameter that differs by about 30% or less, about 25% or less, about 20% or less, about 15% or less, about 10% or less, or about 5% or less. The term “or less” can indicate a range that extends to 0% or to 0.01%.
Although embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features and elements may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the present invention defined in the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.
This application claims the benefit of U.S. Provisional Application No. 62/331,987, filed May 5, 2016, titled “Low Frequency Inductive Heating for Liquids,” and U.S. Provisional Application No. 62/326,824, filed Apr. 24, 2016, titled “Inline Inductive Heater,” each of which is hereby incorporated herein by reference in its entirety.
Number | Name | Date | Kind |
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5006683 | Rapin | Apr 1991 | A |
20050095168 | Centanni | May 2005 | A1 |
20120061382 | Yang | Mar 2012 | A1 |
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20170311393 A1 | Oct 2017 | US |
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62331987 | May 2016 | US | |
62326824 | Apr 2016 | US |