CN110260577B - Supercooling method and cooling system for liquid methane - Google Patents
Supercooling method and cooling system for liquid methane Download PDFInfo
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- CN110260577B CN110260577B CN201910316454.2A CN201910316454A CN110260577B CN 110260577 B CN110260577 B CN 110260577B CN 201910316454 A CN201910316454 A CN 201910316454A CN 110260577 B CN110260577 B CN 110260577B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D29/00—Arrangement or mounting of control or safety devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
- F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
Abstract
The invention provides a liquid methane supercooling method and a liquid methane supercooling system. The supercooling method comprises the following steps: setting the air pillow pressure range of the cooling medium according to the property of the cooling medium, wherein the air pillow pressure of the cooling medium is controlled by a pressure regulating system; and (3) carrying out heat exchange between the cooling medium and the liquid methane to be cooled in the cooling device under the pressure range of the air pillow, so as to obtain the supercooled liquid methane. According to the liquid methane supercooling method and the liquid methane supercooling cooling system, provided by the embodiment of the invention, the air pillow pressure range of the area where the cooling medium is located is set, and the cooling medium is subjected to heat exchange with the liquid methane in the set air pillow pressure range, so that the volatilization phenomenon of the cooling medium can be relieved, the temperature reduction of the cooling medium is avoided, and the liquid methane is effectively prevented from being solidified in the cooling process.
Description
Technical Field
The invention relates to the technical field of rocket propellant cooling, in particular to a liquid methane supercooling method and a liquid methane supercooling system.
Background
The liquid oxygen methane propellant has the characteristics of low cost, no pollution, easy acquisition and the like, and has a wider application prospect in commercial space flight. At present, foreign private space companies including SPACEX, blue origin and the like have applied liquid oxymethane rocket engines to carrier rockets, and liquid rockets taking liquid oxymethane as a propellant have no precedent of application in China.
The liquid propellant can release a large amount of heat in the combustion process of the rocket engine, and the high-heat environment brings great safety hazards to relevant parts (such as a thrust chamber) of the rocket engine. The supercooled liquid methane is beneficial to starting the engine, reduces the pressure in front of a turbopump pump, and improves the precooling effect on the engine.
It is desirable to provide a method for liquid methane cooling that will provide a foundation for the use of liquid methane oxide propellants in liquid launch vehicles.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a liquid methane supercooling method and a cooling system, wherein the liquid methane supercooling method divides liquid methane to be supercooled into at least two flow paths and cools at least one of the flow paths, so that the temperature of the liquid methane can be better controlled, and the performance of a liquid rocket engine is improved.
One aspect of the present invention provides a method for subcooling liquid methane, comprising: setting the air pillow pressure range of the cooling medium according to the property of the cooling medium, wherein the air pillow pressure of the cooling medium is controlled by a pressure regulating system; and (3) carrying out heat exchange between the cooling medium and the liquid methane to be cooled in the cooling device under the pressure range of the air pillow, so as to obtain the supercooled liquid methane.
In one embodiment, the cooling medium is liquid nitrogen and the air pillow pressure ranges from 0.95 MPa to 1.3 MPa.
In one embodiment, the cooling device has a tube side and a shell side, and the performing heat exchange of the cooling medium with the liquid methane to be cooled in the cooling device at the air pillow pressure range to obtain the sub-cooled liquid methane comprises: enabling liquid methane to be cooled to enter the tube side and finish heat exchange with liquid nitrogen entering the shell side; the process of controlling the air pillow pressure of the cooling medium in the air pillow pressure range by the pressure adjusting system is as follows: detecting the air pillow pressure in the shell side where the cooling medium is located; adjusting the air pillow pressure value in the tube pass where the cooling medium is located according to the relation between the air pillow pressure and the air pillow pressure range, wherein when the air pillow pressure is larger than the upper limit of the set air pillow pressure range, an exhaust valve of a shell pass is opened to adjust the air pillow pressure value in the shell pass to the air pillow pressure range; and when the pressure of the air pillow is lower than the lower limit of the set air pillow pressure range, closing the exhaust valve of the tube pass so as to adjust the pressure value of the air pillow in the shell pass to the air pillow pressure range.
In one embodiment, said performing heat exchange of the cooling medium with the liquid methane to be cooled in the cooling device at said gas pillow pressure range comprises: liquid nitrogen is used as a cooling medium to carry out cooling treatment on liquid methane to be cooled; the cooling treatment of the liquid methane to be cooled by taking the liquid nitrogen as a cooling medium comprises the following steps: dividing the liquid nitrogen into at least a first liquid nitrogen flow path and a second liquid nitrogen flow path; carrying out temperature rise treatment on the first liquid nitrogen flow path; and mixing the liquid nitrogen subjected to temperature rise treatment in the first liquid nitrogen flow path with the liquid nitrogen in the second liquid nitrogen flow path, and cooling the liquid methane to be cooled by taking the mixed liquid nitrogen as a cooling medium.
In one embodiment, the cooling device is a kettle reboiler, and the cooling treatment of the liquid methane to be cooled by using the mixed liquid nitrogen as a cooling medium comprises: the method comprises the steps of enabling liquid methane to be cooled to enter a tube side of a kettle-type reboiler and enabling mixed liquid nitrogen to enter a shell side of the kettle-type reboiler, and enabling the liquid methane on the tube side to be cooled through heat exchange with the mixed liquid nitrogen on the shell side.
In one embodiment, a method of subcooling comprises: and detecting the liquid level height of the mixed liquid nitrogen in the shell side by a liquid level meter, and increasing the opening degree of the liquid nitrogen flow control valve when the liquid level height is lower than the lower limit of the set range until the liquid level height in the shell side rises to the set range.
In one embodiment, the states of the control valves in the first liquid nitrogen flow path and the second liquid nitrogen flow path are controlled by a mixed liquid nitrogen temperature parameter, and if the mixed liquid nitrogen temperature is higher than the upper limit of the set range, the flow rate of liquid nitrogen in the second liquid nitrogen flow path is increased and/or the flow rate of liquid nitrogen in the first liquid nitrogen flow path is decreased; and if the temperature of the mixed liquid nitrogen is lower than the lower limit of the set range, increasing the flow rate of the liquid nitrogen in the first liquid nitrogen flow path and/or reducing the flow rate of the liquid nitrogen in the second liquid nitrogen flow path.
In one embodiment, the state of the control valve in the second liquid nitrogen flow path is controlled by the temperature of the mixed liquid nitrogen, and if the temperature of the mixed liquid nitrogen is higher than the upper limit of the set range, the opening degree of the control valve in the second liquid nitrogen flow path is increased so that the proportion of the low-temperature liquid nitrogen is increased; and if the temperature of the mixed liquid nitrogen is lower than the lower limit of the set range, reducing the opening degree of the control valve of the second liquid nitrogen flow path so as to reduce the proportion of the low-temperature liquid nitrogen.
Another aspect of the invention provides a cooling system for liquid methane, comprising: the pressure adjusting module and the heat exchange module; the pressure adjusting module is used for maintaining the pressure of the cooling medium within a preset pressure range, and the heat exchange module is used for enabling the cooling medium to exchange heat with liquid methane to be cooled within the preset pressure range, so that the subcooled liquid methane is obtained.
In one embodiment, the pressure regulation module includes a pressure sensor, a controller, and an exhaust valve; the exhaust valve is communicated with an exhaust pipeline of a space where the cooling medium is located; the pressure sensor is used for detecting the pressure of an area where the cooling medium is located, the controller controls the opening and closing of the exhaust valve according to the relation between the detected pressure and the preset pressure range, and when the detected pressure is smaller than the lower limit of the preset pressure range, the controller controls the exhaust valve to be closed.
According to the liquid methane supercooling method and the liquid methane supercooling system, provided by the embodiment of the invention, the liquid methane can be prevented from being solidified in the cooling process by maintaining the pressure range of the cooling medium, and the cooling effect of the liquid methane is improved
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description, serve to explain the principles of the invention.
FIGS. 1a and 1b are flow diagrams of a liquid methane subcooling process according to an embodiment of the present invention.
FIG. 2 is a flow chart of temperature control of mixed liquid methane in a subcooling process according to an embodiment of the present invention.
Fig. 3 is a flow chart of generation of mixed liquid nitrogen in the supercooling method according to the embodiment of the present invention.
Fig. 4 is a flow chart of the shell side air pillow pressure control in which liquid nitrogen is located in the supercooling method according to the embodiment of the present invention.
Fig. 5-7 are schematic diagrams of cooling systems according to embodiments of the present invention.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.
One aspect of the present invention provides a method for subcooling liquid methane. Referring to fig. 1a, the supercooling method includes:
step S001: setting the air pillow pressure range of the cooling medium according to the property of the cooling medium, wherein the air pillow pressure of the cooling medium is controlled by a pressure regulating system;
step S002: and (3) carrying out heat exchange between the cooling medium and the liquid methane to be cooled in the cooling device under the pressure range of the air pillow, so as to obtain the supercooled liquid methane.
According to the supercooling method provided by the embodiment of the invention, the temperature reduction caused by the gasification process of the cooling medium can be avoided by controlling the pressure of the cooling medium, so that the solidification of liquid methane is avoided.
For example, the cooling medium may be liquid nitrogen, and the air pillow pressure may range from 0.95 to 1.3 MPa. When liquid methane is cooled, liquid nitrogen itself is gasified due to the temperature increase, and absorbs heat during the gasification process, so that the temperature of the cooling medium is reduced. According to the embodiment of the invention, when liquid nitrogen is used as the cooling medium, the temperature of the cooling medium can be prevented from being reduced excessively by controlling the pressure range of the air pillow, so that the solidification phenomenon in the cooling process of the liquid methane is relieved or avoided.
For example, before the liquid methane cooling is started, a range of the air pillow pressure may be preset, the air pillow pressure may be detected by the pressure sensor, and the controller may control the exhaust valve in the area where the air pillow pressure is located to open or close according to the detected air pillow pressure and the set air pillow pressure range. For example, when the air pillow pressure is greater than the upper limit of the preset air pillow pressure range, the controller may control the exhaust valve to open, so that the air pillow pressure is reduced to be within the preset air pillow pressure range; similarly, if the air pillow pressure detected by the pressure sensor is smaller than the lower limit of the air pillow pressure range, the controller controls the exhaust valve to close, so that the air pillow pressure conforms to the air pillow pressure range, the temperature reduction caused by the gasification of the cooling medium is avoided, and the liquid methane is further prevented from being solidified in the cooling process.
Referring to fig. 1b, the supercooling method further includes the steps of:
step S100: dividing liquid methane into at least two flow paths, the two flow paths including a first flow path and a second flow path;
step S200: cooling liquid methane in the first flow path;
step S300: and mixing the liquid methane after cooling in the first flow path with the liquid methane in the second flow path to form the sub-cooled liquid methane.
According to the embodiment of the invention, the liquid methane is divided into two flow paths, and the liquid methane in one flow path is cooled, so that the cooling effect of the liquid methane can be improved, the temperature control precision of the liquid methane supercooling process is improved, and the working performance of the rocket engine is improved.
In the above embodiment, the liquid methane may be divided into a plurality of flow paths, the liquid methane in a part of the flow paths may be cooled at different temperatures, and the differentially cooled liquid methane may be mixed to form the final supercooled liquid methane. According to the embodiment of the invention, the liquid methane in the multiple flow paths is cooled in a temperature difference manner, so that the mixing temperature control precision of the mixed liquid methane is further improved, the gasification phenomenon possibly occurring when high-temperature and low-temperature liquid methane is mixed is reduced, and the utilization rate of the liquid methane is improved.
In one embodiment, the step S100 of splitting the liquid methane into at least two flow paths includes:
the liquid methane is divided into at least two flow paths by a dividing device. For example, the flow diversion device may be a flow diversion valve. For example, liquid methane entering the splitter valve from a single flow path may be split by the splitter valve into two flow paths, wherein the liquid methane in one flow path is cooled and then combined with the liquid methane in the other flow path to form a mixed liquid methane.
Referring to fig. 2, mixing the cooled liquid methane in the first flow path with the liquid methane in the second flow path comprises:
s201: detecting the temperature of the mixed liquid methane; for example, the temperature of the mixed liquid methane may be detected by a temperature sensor. And
s202: and adjusting the state of the flow dividing device according to the temperature, wherein when the temperature is higher than the set upper temperature limit, the flow dividing device is controlled to increase the flow rate of the liquid methane in the first flow path and/or decrease the flow rate of the liquid methane in the second flow path.
According to the liquid methane supercooling method provided by the embodiment of the invention, the temperature of the mixed liquid methane is detected, the state of the diverter valve is adjusted according to the detection result, the liquid methane flow of different flow paths is changed, the temperature control precision in the liquid methane cooling process can be improved, and the cooling effect is improved.
In step S202, if the temperature of the mixed liquid methane detected by the detector is lower than the lower limit of the set temperature, the flow rate of the liquid methane in the first flow path may be reduced and/or the flow rate of the liquid methane in the second flow path may be increased by controlling the flow dividing valve, so that the temperature of the cooled liquid methane may be increased to within the set range.
In one embodiment, the cooling the liquid methane in the first flow path in step S200 includes:
liquid methane in the first flow path is cooled by using liquid nitrogen as a cooling medium.
Referring to fig. 3, the cooling process of the liquid methane in the first flow path using liquid nitrogen as a cooling medium includes:
s204: dividing the liquid nitrogen into at least a first liquid nitrogen flow path and a second liquid nitrogen flow path;
s205: subjecting the first liquid nitrogen flow path to a temperature raising treatment, and
s206: the liquid nitrogen subjected to the temperature raising treatment in the first liquid nitrogen flow path is mixed with the liquid nitrogen in the second liquid nitrogen flow path, and the liquid methane in the first flow path is subjected to cooling treatment using the mixed liquid nitrogen as a cooling medium.
According to the embodiment of the invention, the liquid nitrogen is divided into two flow paths, and one flow path is mixed with the liquid nitrogen after being subjected to temperature rise treatment, so that the temperature control precision of the mixed liquid nitrogen can be improved, and the cooling effect on liquid methane can be improved.
In one embodiment, the cooling of the liquid methane of the first flow path comprises: the liquid methane in the first flow path is caused to enter the tube side of the kettle reboiler, and the mixed liquid nitrogen is caused to enter the shell side of the kettle reboiler, such that the liquid methane on the tube side is cooled by heat exchange with the mixed liquid nitrogen on the shell side. Similarly, as will be appreciated by those skilled in the art, liquid methane may also be fed into the shell side of the kettle reboiler, with mixed liquid nitrogen being fed into the tube side of the kettle reboiler.
In one embodiment, a method of subcooling comprises: the liquid level height of the mixed liquid nitrogen in the shell side is detected through the liquid level meter, and when the liquid level height is lower than the lower limit of the set range, the opening degree of the liquid nitrogen flow control valve is increased (for example, the liquid nitrogen flow control valve can be arranged on a pipeline before liquid nitrogen is split) until the liquid level height in the shell side is increased to be within the set range. Before the liquid methane is subcooled, the liquid level height in the kettle-type reboiler can be set according to the flow of the liquid methane in the first flow path, so that the liquid methane is fully cooled, and the safety and the controllability of the cooling process of the liquid methane are ensured.
In one embodiment, step S200 includes, before cooling the liquid methane in the first stream:
and setting the pressure parameter range of the air pillow in the shell pass to relieve the phenomenon of pipe pass temperature reduction caused by the gasification of liquid nitrogen in the pipe pass, thereby preventing the liquid methane from being solidified. Liquid nitrogen is carrying out the refrigerated in-process to liquid methane, the gasification phenomenon can take place, the gasification of liquid nitrogen can absorb the heat, thereby lead to the temperature reduction in the shell side, and then make the liquid methane in the tube side solidify, under the normal conditions, the gas pillow pressure is higher, the gasification phenomenon of liquid nitrogen is weaker, therefore, through setting for gas pillow pressure range and making liquid nitrogen place shell side pressure maintain in this scope, liquid nitrogen gasification phenomenon can be alleviated, prevent that the temperature in the shell side is showing and is reducing, thereby avoid liquid methane in the cooling process, the solidification phenomenon takes place, improve the utilization ratio of liquid methane.
Referring to fig. 4, the cooling process of the liquid methane in the first flow path in step S200 further includes:
step S207: detecting the air pillow pressure within the shell side, an
Step S208: and controlling the state of a pressure control valve of an exhaust pipeline arranged on the shell side according to the relation between the air pillow pressure parameter range and the detected air pillow pressure, opening the pressure control valve to exhaust if the air pillow pressure is greater than the upper limit of a set value, and closing the pressure control valve if the air pillow pressure is less than the lower limit of the set value so as to maintain the air pillow pressure in the shell side within the set range. According to the liquid methane supercooling method provided by the embodiment of the invention, the gas pillow pressure reference range of the liquid nitrogen is set, so that the solidification phenomenon of the liquid methane in the heat exchange process with the liquid nitrogen can be effectively avoided.
In one embodiment, the state of the flow control valves in the first liquid nitrogen flow path and the second liquid nitrogen flow path is controlled by a mixed liquid nitrogen temperature parameter. And if the temperature of the mixed liquid nitrogen is higher than the upper limit of the set value, increasing the flow rate of the liquid nitrogen in the second liquid nitrogen flow path and/or reducing the flow rate of the liquid nitrogen in the first liquid nitrogen flow path. And if the temperature of the mixed liquid nitrogen is lower than the lower limit of the set value, increasing the flow rate of the liquid nitrogen in the first liquid nitrogen flow path and/or reducing the flow rate of the liquid nitrogen in the second liquid nitrogen flow path. According to the liquid methane supercooling method provided by the embodiment of the invention, the flow rates of the two liquid nitrogen flow paths can be adjusted according to the temperature of the mixed liquid nitrogen, so that the temperature of the mixed liquid nitrogen is in a set range, and the cooling precision of the liquid methane is improved.
In this embodiment, if two liquid nitrogen flow paths are branched by the flow dividing valve, the flow rates of the two flow paths can be simultaneously adjusted by controlling the flow dividing valve. For example, by adjusting the flow divider valve, the flow rate of one flow path can be increased while the flow rate of the other flow path can be decreased. If the two flow paths are respectively provided with the flow valves, the opening degrees of the two flow valves can be respectively adjusted according to the temperature of the mixed liquid nitrogen, so that the flow of a certain liquid nitrogen flow path is increased or reduced or closed.
For example, the temperature of the mixed liquid nitrogen may be adjusted by controlling the flow rate of only one liquid nitrogen flow path. Specifically, the state of the control valve in the second liquid nitrogen flow path is controlled by the temperature of the mixed liquid nitrogen, and if the temperature of the mixed liquid nitrogen is higher than the upper limit of the set value, the opening degree of the control valve in the second liquid nitrogen flow path is increased to increase the proportion of the low-temperature liquid nitrogen, so that the temperature of the mixed liquid nitrogen is reduced under the condition that the flow of the first liquid nitrogen flow path is unchanged. And if the temperature of the mixed liquid nitrogen is lower than the lower limit of the set value, reducing the opening degree of a control valve of the second liquid nitrogen flow path or closing the control valve of the second liquid nitrogen flow path so as to reduce the proportion of low-temperature liquid nitrogen, and further improving the temperature of the mixed liquid nitrogen under the condition that the flow of the first liquid nitrogen flow path is unchanged. According to the liquid methane supercooling method provided by the embodiment of the invention, the temperature of the mixed liquid nitrogen can be quickly adjusted by only adjusting the flow of one liquid nitrogen flow path, so that the cooling process of the liquid methane is simplified.
Another aspect of the invention provides a cooling system for subcooling liquid methane. Referring to fig. 5, the cooling system includes: a splitter module 10, a cooling module 20, and a mixing module 30. The split module 10 is used for splitting the liquid methane to be cooled into at least a first flow path C1 and a second flow path C2. The cooling module 20 is used to cool the liquid methane in the first flow path C1. The mixing module 30 is configured to mix the cooled liquid methane in the first flow path C1 with the liquid methane in the second flow path C2 to form the sub-cooled liquid methane. According to the cooling system provided by the embodiment of the invention, the liquid methane is divided into the two flow paths, and different treatment modes are adopted for the two flow paths, so that the cooling effect of the liquid methane can be improved.
With continued reference to FIG. 6, in one embodiment, the mixing module 30 also includes a controller, temperature detectors 31, 32 (TE, TT, and TI shown in FIG. 6). The diverter module 10 includes a diverter valve TV. The temperature detector is used for detecting the mixed temperature of the liquid methane cooled by the cooling module 20 and the liquid methane in the second flow path C2, and the controller is used for adjusting the opening degree of the diverter valve TV according to the mixed temperature. When the combined temperature is above the upper set temperature limit, the controller controls the diverter valve TV to increase the flow of liquid methane in the first flow path C1 and/or decrease the flow of liquid methane in the second flow path C2. When the combined temperature is below the set lower temperature limit, the controller controls the diverter valve TV to decrease the flow of liquid methane in the first flow path C1 and/or increase the flow of liquid methane in the second flow path C2. According to the embodiment of the invention, the state of the diverter valve is adjusted by mixing the temperature of the liquid methane, so that the cooling effect of the liquid methane can be improved, and the working performance of the rocket engine is improved.
With continued reference to fig. 6, in one embodiment, the cooling module 20 includes a kettle reboiler E1. Wherein the tube side of the first flow path C1 where liquid methane enters the kettle reboiler E1 is cooled by heat exchange with the mixed liquid nitrogen entering the shell side of the kettle reboiler E1 to form subcooled liquid methane. Similarly, liquid methane may enter the pass and be cooled by heat exchange with liquid nitrogen entering the tube pass. The liquid methane in the tube pass of the kettle reboiler exchanges heat with the liquid nitrogen in the shell pass, is cooled, then passes through a flow valve XV and is mixed with the liquid methane in a second flow path C2, and the flow rate of the mixed liquid methane is adjusted by the flow valve XV in the mixing module 30.
Referring to fig. 7, in one embodiment, the cooling system further comprises: and a liquid nitrogen splitting module 40 for splitting the liquid nitrogen into at least a first liquid nitrogen flow path N1 and a second liquid nitrogen flow path N2. And a liquid nitrogen preheating module 50 for heating the liquid nitrogen in the first liquid nitrogen flow path N1 (for example, the liquid nitrogen in the first liquid nitrogen flow path may be heated by an air heater E2 as shown in the figure). And the mixing control module 60 is used for mixing the liquid nitrogen subjected to temperature rise treatment and the liquid nitrogen flowing through the second liquid nitrogen flow path N2, and adjusting the liquid nitrogen flow in the first liquid nitrogen flow path N1 and/or the second liquid nitrogen flow path N2 according to the mixed liquid nitrogen temperature. According to the cooling system provided by the embodiment of the invention, the liquid nitrogen is divided into at least two flow paths, and the liquid nitrogen in the two flow paths is subjected to different treatments, so that the temperature control precision and the temperature control speed of liquid nitrogen cooling can be improved, and the cooling effect on liquid methane is improved.
For example, the blend control module 60 may include temperature sensors and controllers, shown in FIG. 7 as TE, TT, TI before the blended liquid nitrogen enters the kettle reboiler shell side, to adjust the flow rate valve XV of the second liquid nitrogen flow path N2. Specifically, for example, the temperature sensor may measure the mixed liquid nitrogen temperature, and when the mixed liquid nitrogen temperature is higher than the set upper limit, the controller may receive a temperature sensor signal, increase the opening degree of the flow valve TV of the second liquid nitrogen flow path, thereby reducing the mixed liquid nitrogen temperature. When the temperature of the mixed liquid nitrogen is lower than the lower limit of the set value, the controller may receive a temperature sensor signal, reduce the opening degree of the flow valve TV of the second liquid nitrogen flow path or close the flow valve TV of the second liquid nitrogen flow path, thereby increasing the temperature of the mixed liquid nitrogen.
It is known to those skilled in the art that the first liquid nitrogen flow path and the second liquid nitrogen flow path may be controlled by the flow dividing valve such that when the temperature of the mixed liquid nitrogen is higher than the upper limit of the set range, the flow rate of liquid nitrogen in the first liquid nitrogen flow path N1 is simultaneously decreased and the flow rate of liquid nitrogen in the second liquid nitrogen flow path N2 is simultaneously increased by adjusting the flow dividing valve, or when the temperature of the mixed liquid nitrogen is lower than the lower limit of the set range, the flow rate of liquid nitrogen in the first liquid nitrogen flow path N1 is simultaneously increased and the flow rate of liquid nitrogen in the second liquid nitrogen flow path N2 is simultaneously decreased by adjusting the flow dividing valve. According to the cooling system provided by the embodiment of the invention, the mixing control module can adjust the flow of the first liquid nitrogen flow path and/or the second liquid nitrogen flow path according to the outlet temperature of the mixed liquid nitrogen, so that the temperature of the mixed liquid nitrogen is reliably controlled, and the cooling effect on liquid methane is improved.
As shown in fig. 7, the level detection of the kettle reboiler E1 in the foregoing is detected by a level meter IT, and the level height control is controlled by adjusting a flow valve LV, and when the level of the kettle reboiler is lower than a set value, the opening degree of the flow valve LV is increased, and vice versa. In addition, the shell-side pressure of the kettle reboiler is regulated by PE, PI, PV as shown in fig. 7, that is, when the shell-side pressure is higher than the upper limit of the set temperature range, the exhaust pipeline of the shell-side is opened to ensure that the shell-side pressure is within the set range.
It should be noted that the pressure regulation system composed of PE, PI, and PV corresponds to the pressure regulation module of the embodiment of the present invention, and the pressure regulation of the region where the cooling medium is located is realized by detecting and controlling the pressure in the shell side, for example. The kettle reboiler with heat exchange for the liquid methane to be cooled and the liquid nitrogen is one embodiment of the heat exchange module of the embodiment of the invention.
For example, as shown in fig. 7, the pressure regulation module may include a pressure sensor, a controller, and an exhaust valve PV. Wherein the exhaust valve PV communicates with an exhaust line of the space in which the cooling medium is located. The pressure sensor is used for detecting the pressure of the area where the cooling medium is located, and the controller controls the opening and closing of the exhaust valve PV according to the relation between the detected pressure and a preset pressure range, wherein when the detected pressure is smaller than the lower limit of the preset pressure range, the controller controls the exhaust valve PV to close. When the detected pressure is greater than the upper limit of the preset pressure range, the controller controls the exhaust valve PV to open.
The liquid methane supercooling method and the cooling system provided by the embodiment of the invention can better control the temperature of the liquid methane, so that the working performance of the liquid oxymethane engine is improved.
The foregoing is merely an illustrative embodiment of the present invention, and any equivalent changes and modifications made by those skilled in the art without departing from the spirit and principle of the present invention should fall within the protection scope of the present invention.
Claims (7)
1. A method of subcooling liquid methane, comprising:
setting the air pillow pressure range of the cooling medium according to the property of the cooling medium, wherein the air pillow pressure of the cooling medium is controlled by a pressure regulating system;
performing heat exchange between the cooling medium and liquid methane to be cooled in a cooling device under the air pillow pressure range so as to obtain the supercooled liquid methane, wherein the cooling device is a kettle reboiler;
the heat exchange between the cooling medium and the liquid methane to be cooled in the cooling device under the pressure range of the air pillow comprises the following steps:
liquid nitrogen is used as a cooling medium to carry out cooling treatment on liquid methane to be cooled;
the cooling treatment of the liquid methane to be cooled by taking the liquid nitrogen as a cooling medium comprises the following steps:
dividing the liquid nitrogen into at least a first liquid nitrogen flow path and a second liquid nitrogen flow path;
carrying out temperature rise treatment on the first liquid nitrogen flow path;
mixing the warmed liquid nitrogen in the first liquid nitrogen flow path with the liquid nitrogen in the second liquid nitrogen flow path, and
cooling liquid methane to be cooled by taking mixed liquid nitrogen as a cooling medium;
the cooling treatment of the liquid methane to be cooled by taking the mixed liquid nitrogen as a cooling medium comprises the following steps:
the liquid methane to be cooled enters the tube pass of the kettle-type reboiler,
and passing the mixed liquid nitrogen into the shell side of the kettle reboiler, whereby the liquid methane on the tube side is cooled by heat exchange with the mixed liquid nitrogen on the shell side.
2. A subcooling method as described in claim 1, wherein the cooling medium is liquid nitrogen and the air pillow pressure is in the range of 0.95-1.3 MPa.
3. A subcooling method as described in claim 1, wherein the cooling device has a tube side and a shell side, and the subjecting the cooling medium to heat exchange with the liquid methane to be cooled in the cooling device at the air pillow pressure range to obtain subcooled liquid methane comprises:
enabling liquid methane to be cooled to enter the tube side and finish heat exchange with liquid nitrogen entering the shell side;
the process of controlling the air pillow pressure of the cooling medium in the air pillow pressure range by the pressure adjusting system is as follows:
detecting the air pillow pressure in the shell side where the cooling medium is located;
adjusting the air pillow pressure value in the tube pass where the cooling medium is located according to the relation between the air pillow pressure and the air pillow pressure range, wherein when the air pillow pressure is larger than the upper limit of the set air pillow pressure range, an exhaust valve of a shell pass is opened to adjust the air pillow pressure value in the shell pass to the air pillow pressure range; and when the pressure of the air pillow is lower than the lower limit of the set air pillow pressure range, closing the exhaust valve of the tube pass so as to adjust the pressure value of the air pillow in the shell pass to the air pillow pressure range.
4. A supercooling method according to claim 1, wherein states of the control valves in the first liquid nitrogen flow path and the second liquid nitrogen flow path are controlled by a mixed liquid nitrogen temperature parameter, and if the mixed liquid nitrogen temperature is higher than a set upper limit of a range, the flow rate of liquid nitrogen in the second liquid nitrogen flow path is increased and/or the flow rate of liquid nitrogen in the first liquid nitrogen flow path is decreased; and if the temperature of the mixed liquid nitrogen is lower than the lower limit of the set range, increasing the flow rate of the liquid nitrogen in the first liquid nitrogen flow path and/or reducing the flow rate of the liquid nitrogen in the second liquid nitrogen flow path.
5. A supercooling method according to claim 1, wherein the state of the control valve in the second liquid nitrogen flow path is controlled by the temperature of the mixed liquid nitrogen, and if the temperature of the mixed liquid nitrogen is higher than the upper limit of the set range, the opening degree of the control valve in the second liquid nitrogen flow path is increased so that the ratio of the low temperature liquid nitrogen is increased; and if the temperature of the mixed liquid nitrogen is lower than the lower limit of the set range, reducing the opening degree of the control valve of the second liquid nitrogen flow path so as to reduce the proportion of the low-temperature liquid nitrogen.
6. A system for cooling liquid methane, comprising: the device comprises a pressure adjusting module, a liquid nitrogen shunting module, a liquid nitrogen preheating module, a mixing control module and a heat exchange module;
the pressure adjusting module is used for maintaining the pressure of the cooling medium within a preset pressure range;
the liquid nitrogen shunting module is used for shunting liquid nitrogen into at least a first liquid nitrogen flow path and a second liquid nitrogen flow path;
the liquid nitrogen preheating module is used for heating liquid nitrogen in the first liquid nitrogen flow path;
the mixing control module is used for mixing the liquid nitrogen subjected to temperature rise treatment with the liquid nitrogen flowing through the second liquid nitrogen flow path;
and the heat exchange module is used for enabling the mixed liquid nitrogen to exchange heat with the liquid methane to be cooled within the preset pressure range, so that the supercooled liquid methane is obtained.
7. The cooling system of claim 6, wherein the pressure regulation module comprises a pressure sensor, a controller, and an exhaust valve;
the exhaust valve is communicated with an exhaust pipeline of a space where the cooling medium is located;
the pressure sensor is used for detecting the pressure of an area where the cooling medium is located, the controller controls the opening and closing of the exhaust valve according to the relation between the detected pressure and the preset pressure range, and when the detected pressure is smaller than the lower limit of the preset pressure range, the controller controls the exhaust valve to be closed.
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