Patent Application
20250043992
The present invention relates to electric process heaters and more particular to electric process heaters that have baffles.
Electric process heaters have been used for many years in various industries. The design of many process heaters typically involves the use of tubular metal-sheathed heating elements formed into a hairpin shape in which one or more heating elements are arranged in a heating bundle and placed inside a fluid-containment piping system. Although many such designs are known in the art, there remains a need in the industry to improve the effective heat transfer rate of heat produced by the electric heater to the fluid being heated. Many electric process heaters use baffles to redirect the flow of fluid (liquid or gas) over the heating elements to provide improved heat transfer between the heating element and the fluid. However, it has been found that some locations on the baffle may become excessively hot, resulting in degraded performance and shortened lifespan for the heater.
An improved electric process heater is thus highly desirable.
The following presents a simplified summary of some aspects or embodiments of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some embodiments of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present specification discloses an electric process heater comprising a vessel containing a fluid, a plurality of elongated heating elements extending inside the vessel parallel to a central axis of the electric process heater. The heater includes a plurality of baffles disposed at axial intervals inside the electric process heater to redirect the flow of fluid over the heating elements to provide improved heat transfer between the heating elements and the fluid. Each of the plurality of baffles includes flow-through heating element support holes for receiving and supporting the elongated heating elements. Each of the plurality of flow-through heating element support holes has a plurality of element-contacting tabs that protrude radially inwardly to support the heating elements within the baffles, wherein the tabs define a plurality of gaps through which the fluid flows between the baffles and the heating elements to reduce a thermal differential at a heating element-baffle interface.
The present specification also discloses a baffle comprising a plurality of flow-through heating element support holes for receiving and supporting elongated heating elements that transfer heat to the fluid. Each of the plurality of flow-through heating element support holes has a plurality of element-contacting tabs that protrude radially inwardly to support the heating elements within the baffle. The tabs define a plurality of gaps through which the fluid flows between the baffle and the heating elements to reduce a thermal differential at a heating element-baffle interface.
The present specification further discloses an electric process heater comprising a vessel containing a fluid, a plurality of elongated heating elements extending inside the vessel parallel to a central axis of the electric process heater, wherein the heating elements comprise fins. The heater also includes a plurality of baffles disposed at axial intervals inside the electric process heater to redirect the flow of fluid over the heating elements to provide improved heat transfer between the heating elements and the fluid. Each of the plurality of baffles includes flow-through heating element support holes for receiving and supporting the elongated heating elements. Each of the plurality of flow-through heating element support holes has a plurality of element-contacting tabs that protrude radially inwardly to support the heating elements within the baffles, wherein the tabs define a plurality of gaps through which the fluid flows between the baffles and the heating elements to reduce a thermal differential at a heating element-baffle interface.
These and other features of the disclosure will become more apparent from the description in which reference is made to the following appended drawings.
The following detailed description contains, for the purposes of explanation, numerous specific embodiments, implementations, examples and details in order to provide a thorough understanding of the invention. It is apparent, however, that the embodiments may be practiced without these specific details or with an equivalent arrangement. In other instances, some well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention. The description should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
In the embodiment depicted by way of example in
The electric process heater 100 may be an immersion-type heater in which the heating elements are immersed in a fluid to be heated. The electric process heater may also be used or adapted for use in other types of heaters such as flange heaters, pressurized heaters, circulation heaters, etc. The electric process heater may be used in various heating applications for heating a fluid (liquid or gas) for various purposes such as, for example, temperature regulation, freeze protection, vaporization/boiling, stabilizing a condensate, reducing viscosity of a liquid, etc.
As shown by way of example in
In one specific embodiment, illustrated by way of example in
In one specific embodiment, illustrated by way of example in the figures, the first stepped segment 21, the second stepped segment 22 and the third stepped segment 23 have identical shapes.
In one specific embodiment, illustrated by way of example in the figures, the first stepped segment 21, the second stepped segment 22 and the third stepped segment 23 each define 120-degree sectors. When viewed from the end, therefore, the baffle covers 360 degrees. In another embodiment having four stepped segments, each sector would define 90-degree sectors. In another embodiment having five stepped segments, each sector would define 72-degree sectors. In another embodiment having six stepped segments, each sector would define 60-degree sectors. More than six sectors is also possible in other variants. In these embodiments, each sector is identical; however, in yet further embodiments, the sectors may be different (unequal) in size and/or angular span. In the embodiments described so far, the segments of a given baffle cover 360 degrees as noted above; however, in other embodiments, it may be possible to have segments that cover more than 360 degrees or less than 360 degrees.
In one specific embodiment, illustrated by way of example in
In the embodiment illustrated by way of example in
In one specific embodiment, illustrated by way of example in the figures, the first stepped segment 21, the second stepped segment 22 and the third stepped segment 23 have the same number of perforations 16. Such an arrangement provides radial symmetry for the bundle(s) of heating elements inside the vessel. In another embodiment, however, it may be useful for some specific reason or application to provide a different number of perforations 16 on each segment. Similarly, as shown in the figures, the perforations 16 are all the same size (same diameter) in order to accommodate heating elements having a uniform diameter.
In one specific embodiment, illustrated by way of example in the figures, the axial distance between the first segment 21 and the second segment 22 is the same as the axial distance between the second segment 22 and the third segment 23. In another embodiment, the axial distance may be different. The stepped segmental baffle 10 can be made with varying axial distance (pitch) between the steps of the baffle to optimize the heater performance.
The stepped segmented baffle 10 may be manufactured, for example, by separately making each of the segments 12 and then joining the segments together to form the baffle. The stepped segmented baffle is thus easier and less expensive to manufacture than a spiral baffle or a helical baffle. The stepped baffle design with segments being orthogonal to the central axis provides excellent flow characteristics that in turn improve the heat transfer efficiency of the heater.
The baffles 10 may also be used in another type of heat exchanger such as a fluid-to-fluid heater or heat exchanger in which the heating elements are fluid-carrying tubes instead of electric heating elements. In other words, the baffles 10 may be used, or adapted for use, in other types of heat exchangers such as shell-and-tube heat exchanger in which a first fluid is carried through tubes inside a shell (vessel). The tubes extend through holes in baffles to exchange heat with a surrounding second fluid. It will be appreciated that this novel baffle design may find applications and uses in various other types of heat exchangers.
In one embodiment each of the flow-through heating element support holes 16 comprises three equally spaced tabs. In another embodiment, there may be 2 tabs, 4 tabs, 5 tabs or another number of tabs. In the illustrated embodiment, the tabs 17 define an angular arc that is less than an angular arc defined by each of the gaps 19. In another embodiment, the gaps may span an equal or smaller angular arc than the tabs. In the illustrated embodiment, the tabs are equal in size and shape. In another embodiment, the tabs may be different sizes and/or different shapes to accommodate for example a non-circular or asymmetrical heating element. In a main embodiment, the tabs are made of the same material as the rest of the baffle. In another embodiment, the tabs may be made of a different material. The tabs may have the same thickness as the rest of the baffle although in a variant the tabs may have a different thickness. In most embodiments, each hole 16 of each baffle is a flow-through heating element support hole; however, it is possible in some other embodiments that only a subset of the holes 16 are flow-through heating element support holes.
In one embodiment, the heating elements 300 have fins 310. The fins may extend over substantially all of the length of the heating elements or only over portions of the heating elements.
It is to be understood that the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a device” includes reference to one or more of such devices, i.e. that there is at least one device. The terms “comprising”, “having”, “including”, “entailing” and “containing”, or verb tense variants thereof, are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of examples or exemplary language (e.g. “such as”) is intended merely to better illustrate or describe embodiments of the invention and is not intended to limit the scope of the invention unless otherwise claimed.
While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.
In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the inventive concept(s) disclosed herein.
