This invention relates generally to the field of heat exchanger operations. Our immediate interest is in preventing deposition of fouling agents on the surfaces of heat exchangers.
Heat exchange is a fundamental unit operation in nearly all chemical processes, from simple in-home heaters to extraordinarily complex industrial furnaces. Typical industrial heat exchangers are typically blocked by scale formation or deposition of entrained solids. Additionally, cryogenic heat exchangers can also be blocked by constituents in the process fluid condensing out of the process fluid and depositing onto the walls of the heat exchanger. These deposits can not only exacerbate deposition of entrained solids, but can block the heat exchanger independently.
Fouling removal methods are common and can include techniques ranging from the complexity of dismantling the system to manually remove scale to the simplicity of banging on the exchanger with a hammer. However, with few exceptions, these techniques all rely on the heat exchangers being shut down, drained, and dismantled. Even cleaning methods that do not require dismantling require draining and use of a cleaning solution. Effective cleaning of heat exchangers during operations, without shutdown, are needed.
U.S. Pat. No. 4,972,805 to Weems teaches a method and apparatus for removing foreign matter from heat exchanger tubesheets. This disclosure is pertinent and may benefit from the methods disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.
U.S. patent Ser. No. 11/802,617 to Clavenna et al. teaches a method for reducing fouling and the formation of deposits on the inner walls of direct-contact heat exchangers. This disclosure is pertinent and may benefit from the methods disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.
U.S. patent Ser. No. 12/518,863 to Fieler et al. teaches a controlled freeze zone tower. This disclosure is pertinent and may benefit from the methods disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.
A method for preventing fouling of a surface of a process side of an operating heat exchanger is disclosed. A carrier liquid is provided to an inlet of the process side of the operating heat exchanger. The carrier liquid contains a potential fouling agent. The potential fouling agent is entrained in the carrier liquid, dissolved in the carrier liquid, or a combination thereof. The potential fouling agent fouls the surface of the process side of the operating heat exchanger by condensation, crystallization, solidification, desublimation, reaction, deposition, or combinations thereof. A gas-injection device is provided on the inlet of the process side of the operating heat exchanger. A non-reactive gas is injected into the carrier liquid through the gas-injection device. The non-reactive gas will not foul the operating heat exchanger surface and will not condense into the carrier liquid. The non-reactive gas creates a disturbance by increasing flow velocity and creating a shear discontinuity, thereby breaking up crystallization and nucleation sites on the surface of the process side of the operating heat exchanger. In this manner, fouling of the operating heat exchanger is prevented.
The carrier liquid may be water, brine, hydrocarbons, liquid ammonia, liquid carbon dioxide, or combinations thereof. The non-reactive gas may be nitrogen, argon, helium, and hydrogen. The potential fouling agent may be solid particles, miscible liquids, dissolved salts, a fouling gas that may desublimate onto the surface of the operating heat exchanger, or combinations thereof. The fouling gas may be carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, hydrocarbons with a freezing point above 0 C, or combinations thereof.
The gas-injection device may be aluminum, stainless steel, polymers, carbon steel, ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, or combinations thereof. The gas-injection device may be a nozzle or a plurality of nozzles. The nozzle may be oriented perpendicular to the inlet of the process side of the operating heat exchanger. The plurality of nozzles may be evenly spaced in a staggered, rotating pattern around the inlet and may be oriented perpendicular to the inlet of the process side of the operating heat exchanger. The plurality of nozzles may be evenly spaced around and may be oriented perpendicular to the inlet of the process side of the operating heat exchanger.
The nozzle may be oriented to inject the cleaning gas at an acute angle away from the inlet to the process side of the operating heat exchanger. The plurality of nozzles may be evenly spaced in a ring around the inlet to the process side of the operating heat exchanger and may be oriented to inject the cleaning gas at an acute angle towards the inlet to the process side of the operating heat exchanger. The plurality of nozzles may be placed in a staggered, rotating pattern around the inlet to the process side of the operating heat exchanger and may be oriented to inject the cleaning gas at an acute angle towards the inlet to the process side of the operating heat exchanger.
The gas-injection device may be a sparger or plurality of spargers. The sparger may be a membrane sparger, porous sintered metal sparger, or orifice sparger. The plurality of spargers may be membrane spargers, porous sintered metal spargers, orifice spargers, or combination thereof.
The mixing chamber may be provided after the gas-injection device but before the inlet to the process side of the operating heat exchanger. The mixing chamber may be aluminum, stainless steel, polymers, carbon steel, ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.
The operating heat exchanger may be a brazed plate, aluminum plate, shell and tube, plate, plate and frame, plate and shell, spiral, or plate fin style heat exchanger. The process side of the heat may be aluminum, stainless steel, polymers, carbon steel, ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.
In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:
It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention.
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In some embodiments, the carrier liquid may be water, brine, hydrocarbons, liquid ammonia, liquid carbon dioxide, or combinations thereof. The non-reactive gas may be nitrogen, argon, helium, hydrogen, air, or combinations thereof. The potential fouling agent may be solid particles, miscible liquids, dissolved salts, a fouling gas that may desublimate onto the surface of the operating heat exchanger, or combinations thereof. The fouling gas may be carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, hydrocarbons with a freezing point above 0 C, or combinations thereof.
In some embodiments, the gas-injection device may be aluminum, stainless steel, polymers, carbon steel, ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, or combinations thereof. The gas-injection device may be a nozzle, a plurality of nozzles, a sparger or a plurality of spargers. The nozzle or nozzles may be oriented perpendicular to the inlet of the process side of the operating heat exchanger. In instances where there are a plurality of nozzles, the nozzles may be evenly spaced or placed in a staggered, rotating pattern around the inlet. and may be oriented perpendicular to, or at an acute angle towards or away from, the inlet of the process side of the operating heat exchanger.
In some embodiments, the sparger or spargers may be a membrane sparger, porous sintered metal sparger, orifice sparger, or combinations thereof.
In some embodiments, a mixing chamber may be provided after the gas-injection device but before the inlet to the process side of the operating heat exchanger. The mixing chamber may be aluminum, stainless steel, polymers, carbon steel, ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.
In some embodiments, the operating heat exchanger may be a brazed plate, aluminum plate, shell and tube, plate, plate and frame, plate and shell, spiral, or plate fin style heat exchanger. The process side of the operating heat exchanger may be aluminum, stainless steel, polymers, carbon steel, ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.
This invention was made with government support under DE-FE0028697 awarded by The Department of Energy. The government has certain rights in the invention.
Number | Name | Date | Kind |
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20120000626 | Watson | Jan 2012 | A1 |
20180292150 | Brumfield | Oct 2018 | A1 |
Number | Date | Country | |
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20180231336 A1 | Aug 2018 | US |