JP2015502518A - Internal baffle for sloshing suppression in core heat exchanger in shell - Google Patents

Abstract

An apparatus and method for suppressing sloshing in a core-in-shell heat exchanger is provided. In one embodiment, the heat exchanger comprises (a) an internal volume defined within the shell, (b) spaced apart cores disposed within the shell internal volume, and (c) spaced apart cores. A sloshing restraining baffle disposed within the internal volume for separation, each core being partially immersed in a liquid shell side fluid, wherein the sloshing restraining baffle is a restriction of the liquid shell side fluid between each core The sloshing suppression baffle can withstand cryogenic temperatures, and the sloshing suppression baffle can withstand and deflect the liquid shell side flow between each core. [Selection] Figure 1

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is hereby incorporated by reference in its entirety, as of December 20, 2011, which is hereby incorporated by reference herein under 35 USC §119 (e). Claimed priority benefit of US Provisional Patent Application No. 61 / 578,133 filed and filed Dec. 18, 2012 “To reduce the effects of motion in a core heat exchanger in a shell. Method and apparatus ".

FIELD OF THE INVENTION This invention relates to baffles for controlling sloshing in a core-in-shell heat exchanger.

BACKGROUND OF THE INVENTION Natural gas in its natural state cannot be transported economically unless it is concentrated. Recently, the use of natural gas has increased significantly due to its environmentally friendly and clean combustion characteristics. Natural gas combustion is important because it produces less carbon dioxide than other fossil fuels, and carbon dioxide emissions are recognized as an important factor in causing the greenhouse effect. Liquefied natural gas (LNG) may be increasingly used in densely populated urban areas with increasing interest in environmental issues.

  Abundant reserves of natural gas exist throughout the world. Many of these gas reserves are located offshore where they cannot be accessed from land, and are considered to be stranded gas reserves based on the application of existing technology. Existing technical gas reserves are replenished faster than oil reserves, which makes the use of LNG more important to meet future energy consumption demands. Liquid LNG occupies 600 times less space than gaseous natural gas. Many regions of the world cannot be reached on the pipeline due to technical, economic or political restrictions, so voyage to install LNG treatment plant offshore and to carry offshore LNG directly from treatment plant to transport ship Using a ship can reduce initial capital investment or otherwise make uneconomical offshore reserves available.

  Floating liquefaction plants provide an offshore alternative to onshore liquefaction plants and an expensive alternative to costly submarine pipelines for stranded gas offshore reserves. The floating liquefaction plant can be moored offshore or near a gas field or in a gas field. It also means that a gas field becomes a movable asset that can be relocated to a new location if it is nearing the end of its production life or if demanded by economic, environmental or political conditions.

  One problem encountered with floating liquefaction vessels is the sloshing of vaporizing fluid in the heat exchanger. Sloshing in the heat exchanger can result in the generation of forces that can affect the stability and control of the heat exchanger. If the vaporizing fluid is allowed to sloshing freely in the heat exchanger shell, the moving fluid can adversely affect the thermal function of the heat exchanger core. In addition, the periodic nature of the motion can cause periodic behavior in the heat transfer efficiency, thus processing conditions in the LNG liquefaction plant can be affected. These instabilities result in poorer overall plant performance, leading to narrower operating ranges and limitations on available production capacity.

  Therefore, there is a need for a sloshing suppression baffle to reduce the effects of movement in the core-in-shell heat exchanger.

SUMMARY OF THE INVENTION In one embodiment, a heat exchanger comprises (a) an internal volume defined within a shell, (b) spaced apart cores disposed within the internal volume of the shell, and (c) spaced apart. A sloshing restraining baffle disposed within the internal volume for separating a plurality of cores, wherein each core is partially immersed in a liquid shell side fluid, and the sloshing restraining baffle Allowing a limited distribution of shell side fluid, the sloshing suppression baffle can withstand cryogenic temperatures, and the sloshing suppression baffle can withstand and deflect the flow of liquid shell side fluid between each core.

  In another embodiment, a method for reducing the effects of motion in a heat exchanger, wherein the heat exchanger includes an internal volume defined within a shell, the internal volume within the shell being spaced apart. (A) installing a sloshing suppression baffle in the internal volume in the shell, wherein the sloshing suppression baffle separates a plurality of spaced cores in the internal volume; ) Partially immersing each core in a liquid shell side fluid, wherein the sloshing restraining baffle allows a limited distribution of the liquid shell side fluid between each core; and (c) in each core Introducing a core-side fluid; (d) cooling the core-side fluid thereby generating a cooled flow in each core; and (e) extracting the cooled flow from each core. .

The invention, together with further advantages thereof, can be understood by reference to the following description taken in conjunction with the accompanying drawings.
It is the schematic of a core type heat exchanger in a shell. 1 is a schematic view of a core-in-shell heat exchanger according to an embodiment of the present invention. 1 is a schematic view of a core-in-shell heat exchanger according to an embodiment of the present invention. 1 is a schematic view of a core-in-shell heat exchanger according to an embodiment of the present invention. 1 is a schematic view of a core-in-shell heat exchanger according to an embodiment of the present invention. 1 is a schematic view of a core-in-shell heat exchanger according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Any specific examples are exemplary and not limiting. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used to obtain further embodiments in other embodiments. Accordingly, the present invention is intended to embrace such modifications and variations as fall within the scope of the appended claims and their equivalents.

  Referring to FIG. 1, the heat exchanger 10 is generally illustrated including a shell 12 and a plurality of spaced apart cores, a first core 16, a second core 18, and a third core 20. The spaced apart cores in the heat exchanger include at least two cores. The shell 12 has an interior volume 14 and is substantially cylindrical and is defined by an upper sidewall 22, a lower sidewall 24 and a pair of end caps 26. For illustrative purposes, the heat exchanger is positioned horizontally. However, the heat exchanger can be arranged in any commercially operable manner, for example vertical.

  The first core 16, the second core 18, and the third core 20 are disposed inside the internal volume 14 of the shell, and are partially immersed in the liquid shell-side fluid. In one embodiment, the liquid shell side fluid is a fluid to be vaporized, i.e., a refrigerant. The liquid shell side fluid and core side fluid flow through each core in a countercurrent or crossflow manner.

  The spaced apart cores each receive a separate core side fluid and allow simultaneous indirect heat transfer between the liquid shell side fluid and the separate core side fluid.

  The design principle behind the core-in-shell heat exchanger is the cross-exchange of the core side fluid with the liquid shell side fluid. A liquid shell side fluid is present in the pressure vessel where a brazed aluminum compact exchanger core is attached and immersed in the liquid shell side fluid at or near the boiling point. The liquid is drawn into the bottom of the exchanger where it contacts the hotter surface in the core. The liquid shell side fluid then transfers heat through the exchanger core flow path. Most of the heat transfer is due to the latent heat of vaporization of the liquid shell side fluid. The core side fluid is cooled or condensed as it passes through the opposite side of the flow path in the exchanger core.

  The thermal and hydraulic performance of the core-in-shell heat exchanger depends on the liquid level in the exchanger. The driving force for the circulation of the liquid shell side fluid to the exchanger core is the thermosyphon effect. The thermosyphon effect is a passive fluid movement phenomenon caused by the force of natural convection heat. As fluid evaporation occurs, the fluid is heated and becomes lighter and fluid density decreases. As it naturally flows upward in the flow path, new liquid is drawn. This results in the natural circulation of the liquid shell side fluid to the core flow path induced by the temperature gradient inside the core. Instead of vaporizing all the liquid in the flow path, the liquid and vapor mixture is transported through the exchanger core flow path and discharged from the top of the core. A suitable space for separating the gas and the liquid must be provided above the core so that only the gas leaves the overhead part on the shell side of the core. The liquid separated at the top of the exchanger is then recycled to the bottom of the container where it is then vaporized in the core. The driving force for separation of gas and liquid at the upper part of the core-in-shell heat exchanger is gravity.

  The thermosiphon circulation effect inside the core is enhanced or reduced by the external hydraulic pressure (level difference) between the effective liquid level inside the core relative to the liquid level outside the core. When the liquid level in the shell is lowered, the driving force for transporting the liquid into the exchanger core is lowered, and the efficient heat conduction is reduced. When the liquid level drops below the core, the circulation of the liquid shell side fluid stops due to the loss of the thermosyphon effect, resulting in a loss of heat transfer. When the heat exchanger is operating at a higher liquid level (immersion) than the core, the heat conducted is further reduced because the vapor generated in the core needs to get over the additional head to be exhausted from the core To do. More severe conditions are those where the liquid level is below the core of the exchanger, which reduces heat exchange to near zero.

  As described above, sloshing of the vaporized fluid inside the heat exchanger can affect the stability and control of the exchanger. Furthermore, the periodicity of movement will lead to the periodic behavior of heat transfer efficiency and thus process conditions in the LNG liquefaction plant. These instabilities can lead to poorer overall plant performance and will result in narrower operation.

  The sloshing suppression baffle of the present invention reduces the effects of motion on the in-shell core heat exchanger. A sloshing suppression baffle is disposed within the internal volume of the shell to separate the spaced apart cores. Each sloshing suppression baffle allows limited distribution of the liquid shell side fluid between each core. The sloshing suppression baffle can withstand cryogenic temperatures. The sloshing suppression baffle can withstand and deflect the shell side flow of liquid between each core.

  Referring to FIG. 2, the sloshing restraint baffle 28 is a solid plate for providing reduced sloshing of the liquid shell side fluid in the heat exchanger 10. The solid plate sloshing suppression baffle 28 includes a baffle bottom opening that allows limited distribution of liquid shell side fluid between the cores. The height of the solid plate sloshing suppression baffle 28 depends on the expected degree of movement. In one embodiment, the height of the solid plate sloshing suppression baffle is at or near the top of the core assembly. The arrangement and size of the baffle is important because of the potential impact on the movement applied at the bottom of the core and the resulting thermosyphon effect. What is important for the size of the opening is to ensure that the thermosyphon effect is not compromised.

  Referring to FIG. 3, the sloshing suppression baffle 30 is a perforated plate disposed at the center of the core to attenuate the influence of movement. In one embodiment, the perforated plate anti-sloshing baffle is a single plate. In another embodiment, the anti-slosh perforated plate is a double plate with matching holes. With the double plate, the liquid to be vaporized must be further decelerated in order to redirect and pass through the second plate. A solid plate sloshing suppression baffle 28 is also illustrated between each core. This embodiment distributes the liquid more evenly, has less impact on movement under the core and has minimal impact on the thermosyphon.

  Referring to FIG. 4, sloshing restraining baffles 32, 34, 36, 38, 40 and 42 are located at the end of each core assembly. The sloshing suppression baffle can be a solid plate, a perforated plate, or a combination thereof. In one embodiment, the area between each core assembly remains empty. In another embodiment, the area between each core assembly is filled with a filler that damps the flow motion.

  Referring to FIG. 5, the sloshing restraining baffle is placed horizontally between the cores to ensure that the upward momentum is reduced. The sloshing suppression baffle can be a solid plate, a perforated plate, or a combination thereof.

  Referring to FIG. 6, a cornered or rounded sloshing suppression baffle is used to reduce wave motion over the top of the core, potentially resulting in excessive liquid entrainment due to liquid floating into the vapor separation space. , Placed at or near the top of the core assembly to reorient the liquid away from the top of the core assembly.

  Any one or combination of the described sloshing suppression baffles can be utilized to effectively and efficiently reduce the effects of motion on the heat exchanger.

  In addition to the installation of motion-suppressing baffle plates, certain types of filling materials suitable for cryogenic services, such as stainless steel structured or random filling materials, can provide free space in the shell to restrain movement. Can be added to. A structured or random filler alone is unlikely to give enough pressure drop to drop the momentum of the moving fluid, but can be used in combination with a baffle plate for motion damping .

  Because the length of these heat exchangers is usually large, even very small wave motions can have a dramatic impact on the performance of the core-in-shell exchanger. A narrow operating range leads to sensitivity to movement. By carefully considering the placement of the motion-reducing baffle, the compact design of the core-in-shell heat exchanger can work in a moving environment, avoiding alternatives such as shell and tube exchangers Can be done and thus save considerable costs.

  Finally, it should be noted that discussions in any reference, particularly references that are issued after the priority date of the present invention, are not admitted to be prior art to the present invention. At the same time, all the following claims are incorporated into this detailed description and specification as additional embodiments of the invention.

  Although the arrangements and methods described herein have been described in detail, it should be noted that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. is there. One skilled in the art can explore more preferred embodiments and find other ways to implement the invention that are not as accurate as described herein. The inventor intends that modifications and equivalents of the invention belong to the scope of the claims, and that the detailed description, summary, and drawings are not used to limit the scope of the invention. It is intended that the invention be as broad as the following claims and their equivalents.

Claims (26)

(A) an internal volume defined within the shell;
(B) a plurality of spaced apart cores disposed within the internal volume of the shell; and (c) a sloshing control baffle disposed within the internal volume for separating the plurality of cores, each core being a liquid Partly immersed in the shell side fluid of the liquid, the sloshing suppression baffle allows a limited distribution of the liquid shell side fluid between each core, the sloshing suppression baffle can withstand cryogenic temperatures, and Sloshing suppression baffle is a heat exchanger that can withstand the flow of liquid shell side between each core and deflect it.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is installed between the cores.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is installed in a central portion of the core.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is installed between the cores and in a central portion of the cores.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is a solid plate, and the solid plate includes a flow path in the vicinity of the bottom of the internal volume in the shell.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is a perforated plate.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is a double perforated plate.   The heat exchanger according to claim 1, wherein the sloshing suppression baffle is disposed at an end of each core.   9. A heat exchanger according to claim 8, wherein the area between the sloshing suppression baffles is filled with a filling material.   The heat exchanger according to claim 1, wherein a region between the sloshing suppression baffles is filled with a filling material.   The heat exchanger according to claim 1, wherein the liquid shell side fluid is a fluid to be vaporized.   The heat exchanger according to claim 11, wherein the liquid shell-side fluid is a refrigerant. A method for reducing the effects of movement within a heat exchanger, wherein the heat exchanger includes an internal volume defined within a shell, the internal volume including a plurality of spaced cores;
a. Installing a sloshing-suppressing baffle within an internal volume within the shell, wherein the sloshing-suppressing baffle separates a plurality of cores within the internal volume;
b. Partially immersing each core in a liquid shell-side fluid, wherein the sloshing-inhibiting baffle allows limited distribution of the liquid shell-side fluid between each core;
c. Introducing a core side fluid into each core;
d. Cooling the core side fluid thereby generating a cooled flow within each core; and e. Removing the cooled stream from each core.   The method of claim 13, wherein the sloshing suppression baffle is placed between each core.   The method of claim 13, wherein the sloshing suppression baffle is installed in the center of the core.   14. The method of claim 13, wherein the sloshing suppression baffle is installed between each core and in the center of the core.   The method of claim 13, wherein the sloshing suppression baffle is a solid plate, and the solid plate includes a flow path near a bottom of an internal volume in the shell.   The method of claim 13, wherein the sloshing suppression baffle is a porous plate.   The heat exchanger according to claim 13, wherein the sloshing suppression baffle is a double porous plate.   The method of claim 13, wherein the sloshing suppression baffle is disposed at the end of each core.   21. The method of claim 20, wherein the area between the sloshing suppression baffles is filled with a filling material.   14. The method of claim 13, wherein the area between the sloshing suppression baffles is filled with a filling material.   14. The method of claim 13, wherein the sloshing suppression baffle can withstand cryogenic temperatures.   14. The method of claim 13, wherein the sloshing suppression baffle can withstand and deflect the flow of refrigerant between each core.   The heat exchanger according to claim 13, wherein the liquid shell side fluid is a fluid to be vaporized.   The heat exchanger according to claim 25, wherein the liquid shell-side fluid is a refrigerant.

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