Patent Application
20210352782
The present description generally relates to apparatuses and methods for heating a fluid flowing through tubing. More particularly, the description relates to apparatuses and methods incorporating one or more microwave heating devices.
Currently, there are limited industrial applications of microwave heating technology since this technology can be considered expensive in terms of capital cost and energy conversion. However, there has been a recent surge in studies elucidating the fundamentals of microwave-matter interactions, and the number of chemical processes that could feasibly benefit from microwave technology is growing.
Processes such as hydrocarbon cracking, NOx reduction and SOx reduction have been successfully carried out in laboratory scale microwave reactors. A laboratory scale reactor that has been used for ethane cracking comprises a straight quartz tube, through which ethane flows, surrounded by microwave emitters. Quartz is “transparent” to microwave radiation; thus, microwaves can pass through the quartz to heat the ethane within the tube.
Hydrocarbon cracking plants, particularly steam cracking plants, are some of the most energy intensive plants in the chemical industry. A typical steam cracking furnace comprises a number of tubing coils through which a hydrocarbon and steam mixture flows. A number of burners surround the tubing coils in what is known as the radiant section and heat the tubing primarily by radiant heat transfer. The fuel for these burners can be expensive and its combustion products can be harmful to the environment. It is believed that implementing microwave technology in processes that can be considered harmful to the environment, such as steam cracking, can reduce the carbon footprint and/or operating costs associated with such processes.
Applicant's co-pending PCT application no. PCT/CA2018/051507, entitled “Removable Bend in Tubing for Industrial Process Equipment” (the entire content of which is incorporated herein by reference), discloses an apparatus developed, at least in part, to address one or more of the above drawbacks.
However, most industrial scale chemical processes employ equipment made primarily from carbon steel. It is known that exposing certain metals, such as carbon steel, to microwave radiation can cause electrical sparks which can, in turn, have destructive effects such as burning holes in metal surfaces. Such sparks can also damage microwave emitters and/or generate a surge that can damage sensitive microelectronics.
There is a need for an improved method and apparatus for microwave heating of fluid in tubes.
In one aspect, there is provided an apparatus for heating a fluid, the apparatus comprising: a first and second bend portion each having first and second ends; the first end of the first bend portion being removably attached to an upstream tube; the second end of the first bend portion being removably attached to the first end of the second bend portion such that the first and second bend portions are in fluid communication; the second end of the second bend portion being removably attached to a downstream tube; each bend portion including at least one microwave emitter; and a support structure containing the first and second bend portions.
In another aspect, there is provided an apparatus for heating a fluid, the apparatus comprising: a tube; a first end and a second end, the tube being interposed therebetween; an opening intermediate the first and second ends; the first end being removably attached to an upstream tube; the second end being removably attached to a downstream tube; the tube having a channel defined therein, the channel having a diameter larger than an inner diameter of the upstream tube; the channel being in fluid communication with the upstream and downstream tubes; and the opening having a microwave emitter positioned therein.
The present description is illustrated by way of example only with reference to the appended drawings wherein:
It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the example embodiments described herein. Also, the description is not to be considered as limiting the scope of the example embodiments described herein.
The terms “comprise”, “comprises”, “comprised” or “comprising” may be used in the present description. As used herein (including the specification and/or the claims), these terms are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not as precluding the presence of one or more other feature, integer, step, component or a group thereof as would be apparent to persons having ordinary skill in the relevant art. Thus, the term “comprising” as used in this specification means “consisting at least in part of”. When interpreting statements in this specification that include the term “comprising”, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as “comprise” and “comprised” are to be interpreted in the same manner.
It will be appreciated that the term microwave emitter used herein refers to any type of microwave emitter.
It will also be appreciated that the term “flanged spool piece” used herein refers to a pipe section or segment. In most cases, and as known in the art, a spool has flanges provided on one or both ends.
The term “and/or” can mean “and” or “or”.
One or more of the terms “vertical”, “vertically”, “horizontal”, “horizontally”, “top”, “bottom”, “upwardly”, “downwardly”, “upper”, “lower”, “inner” and “outer” are used throughout this specification. It will be understood that these terms are not intended to be limiting. These terms are used for convenience and to aid in describing the features herein, for instance, as illustrated in the accompanying drawings.
Microwave heating can be utilized in chemical reactions or processes including, but not limited to, hydrocarbon cracking, catalytic heterogeneous reactions, disposal of hazardous waste, food processing, drying processes and pyrolysis of various organic wastes. Such organic wastes can include, but are not limited to, biomass, sludge, oil shale and plastic waste. It will be appreciated that the equipment discussed herein can be used in combination with or replace heating methods currently used in one or more of the chemical processes discussed above.
More generally, any chemical process wherein it is desirable to heat a fluid being conveyed through tubing, and wherein at least one of the involved chemical and/or physical transformations can be facilitated using microwave radiation, can benefit from the apparatus discussed herein.
During operation of the steam cracking furnace 100, coke builds up within the tubing coils within the convection section 101 and the radiant section 102. Coke builds up particularly quickly in the coils in the radiant section 102, the hottest section in the furnace, and can hinder heat transfer from the burners to hydrocarbons flowing through the radiant coils. In steam cracking furnaces, the residence time of the hydrocarbons in the radiant coils is often less than half a second. Too long of a residence time can result in excessive coke buildup and poor selectivity.
In an example embodiment, the microwave heating apparatus discussed further below can replace the lower, or radiant portion of one or more steam cracking furnaces in a steam cracking plant. The microwave heating apparatus can also be inserted into an existing firebox (i.e., the walls of the radiant section). It is postulated that implementing the equipment discussed below can reduce operating costs and/or the carbon footprint of steam cracking processes.
It will be appreciated that the removable bend portion 201 may optionally comprise one or more microwave absorbing materials including, but not limited to ceramic materials, metal oxides, or carbon-containing materials. The removable bend portion 201, preferably the inner bend 207, may optionally comprise microwave transparent materials including, but not limited to quartz. Microwaves from the emitter 202 can pass through the quartz included in inner bend 207 to heat the fluid flowing through the bend portion 201 and/or to heat the inner surface of the bend portion 201. The bracing surface 205 of the bend can provide support for the inner bend 207. The seating surface 205 and an inner surface 209 of the bend portion 201 may optionally include materials that reflect microwaves to contain same within the bend portion 201.
It will be appreciated that other parts of the bend portion 201, such as seating surface 206, may optionally comprise microwave absorbing materials such as those discussed further herein.
As discussed in greater detail below, the support system 400 can be cooled by being exposed to the external environment or by actively circulating a cooling fluid, such as air, over the support system 400. The air may be circulated by means such as fans. The support system 400 can also include an external cooling jacket through which a fluid such as water can flow and absorb heat from the system. Cooling the support system 400 can help to reduce the thermal cycling of the support portions 401 and/or the removable bend portions 201 resulting from repeatedly transitioning between high and low temperature conditions.
It can be appreciated that a radiant heating means, such as methane powered furnace guns, can optionally be disposed within the insulated section 601 to provide heat to supplement the heating resulting from microwave irradiation as described herein.
Each push mechanism 602 comprises a jacking bracket 606, which comprises a flange 607 that is fastened to the support flange 402, such as by bolts 611 and nuts 612. Jack screws 605 extend from the jacking bracket 606 to the external bracing surface 205 and can be turned to push the curved seating surface 206 toward the support surface 403, thereby retaining seating surfaces 203 against one another.
The heating apparatus 600 comprises a blind flange 615 that is connected to flange 607 via bolts 611 and nuts 612. Although bolts and nuts are shown, it will be appreciated that other clamping mechanisms or mechanical fasteners could be used.
The example push mechanisms 602 in
A first space 614 is defined between the jacking bracket and the blind flange. A second space 613 is defined between the jacking bracket and the bend portion 201. The spaces 613 and 614 can be pressurized, in the presence or absence of insulation, to assist in retaining the bend portions 201 together. The insulation can include commonly used furnace lining insulation. Examples of materials commonly used in furnace insulation include but are not limited to polycrystalline wool, refractory ceramic fiber, and low bio-persistent fiber. The spaces 613 and 614 can include inert gas at a higher pressure than the fluid flowing through the conduit 200 to prevent fluid from escaping from conduit 200. If inert gases leak into the conduit 200 and mix with the fluid flowing therethrough, they are unlikely to participate in whatever reactions might be taking place.
Turning to
Turning to
In another example embodiment of the flanged spool piece, the openings can be adapted to receive a conical insert. Thus, the lower slot would be narrower than upper opening to receive such insert.
It will be understood that although the tubes 800, 900 and 1002 (discussed below) are depicted as being straight, the principles discussed above can be applied to tubes having other shapes such as U-bends, V-bends, 90-degree bends etc.
It can be appreciated that the internal diameter of the liners 806 and 902 can be larger than, equal to, or lesser than the inner diameter of the open ends 911 and 912. A purpose of having an internal diameter larger than that of the open ends is discussed with respect to
The removable liner 905 can be mechanically retained within slot 904b in the manner discussed below with respect to
In another example embodiment, more than one flanged spool piece 850, 950 and/or 1002 (
An outer support jacket 1101 is mounted to the tube 900 by means such as welding and extends radially outward from tube 900. The outer support jacket 1101 includes a support flange 1102. A flange 1107 extending from a jacking bracket 1106 is fastened to a support flange 1102, such as by bolts 1110 and nuts 1112. The jack screws 1105 exert a force on bracing layer 914 to retain the removable liner in slot 904b, thereby aligning channels 906 and 910. A blind flange 1115 is fastened to jacking bracket 1106 by bolts 1110 and nuts 1112. Although bolts and nuts are shown, it will be appreciated that other clamping mechanisms or mechanical fasteners can be used.
A first space 1114 is defined between the jacking bracket 1106 and the blind flange 1115. A second space 1113 is defined between the jacking bracket 1106 and the pipe insert 908. The spaces 1113 and 1114 can be pressurized, in the presence or absence of insulation, to assist in retaining the pipe insert 908 and/or to prevent fluid flowing through channels 910 and 906 from escaping if the seal is comprised. As noted above, the insulation can also include commonly used furnace lining insulation if the fluid in the tubing is at high temperatures. Examples of materials commonly used in furnace insulation include but are not limited to polycrystalline wool, refractory ceramic fiber, and low bio-persistent fiber.
Turning to
In the present description, reference is made to a “spool” or a “spool piece”. As noted above, such terms typically refer to a pipe segment having flanges on opposing ends and which are generally used to connect to adjacent pipe segments on each end. While, as noted above, the presently described microwave devices are particularly suited for utilization on spools, it will be understood that such devices may be used on any pipe segment, whether or not a spool. Thus, it will be understood that the reference to “spool” in the present description is intended to include any pipe segment where the present heating devices may be incorporated.
It will also be appreciated that different features of the example embodiments of the system, the method and the apparatus, as described herein, may be combined with each other in different ways. In other words, different modules, operations and components may be used together according to other example embodiments, although not specifically stated.
Although the above has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the scope of the claims appended hereto.
This application claims priority to U.S. Provisional Patent Application No. 62/746,222, filed on Oct. 16, 2018, and U.S. Provisional Patent Application No. 62/843,732, filed on May 6, 2019. The entire contents of the aforementioned applications are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2019/051467 | 10/16/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62746222 | Oct 2018 | US | |
| 62843732 | May 2019 | US |
