Heating system for air separation plant

Abstract

The utility model discloses a heating system for air separation equipment, and relates to the technical field of air separation. The heating system comprises a device to be heated; the backup liquid nitrogen storage tank is used for storing liquid nitrogen; the liquid nitrogen pump is connected with the backup liquid nitrogen storage tank; the heating device comprises a steam type water bath vaporizer and an electric heater; the steam type water bath vaporizer is connected with the liquid nitrogen pump and is used for heating liquid nitrogen provided by the liquid nitrogen pump; the electric heater is connected with the output end of the steam type water bath vaporizer and used for heating liquid nitrogen flowing out of the steam type water bath vaporizer. The first valve is connected between the output end of the steam type water bath vaporizer and the to-be-heated device and is used for connecting or disconnecting the steam type water bath vaporizer and the to-be-heated device; the controller is electrically connected with the liquid nitrogen pump, the electric heater and the first valve; and the discharge pipeline is connected with the to-be-heated device and is used for discharging the liquid nitrogen flowing out of the to-be-heated device.

Description

Technical Field

[0001] This utility model relates to the field of air separation technology, and in particular to a heating system for air separation equipment. Background Technology

[0002] In related technologies, the heating gas for the cold box in air separation equipment is supplied by air after molecular sieve operation. Under normal circumstances, if the initial start-up or shutdown of the air separation equipment exceeds 48 hours, the cold box needs to be drained and heated until the dew point inside the cold box is within acceptable limits before proceeding to the next step. Before each start-up of the air separation equipment, the air compressor unit needs to be started in advance and the cold box needs to be heated using the molecular sieve system. The heating time is usually long (generally more than 36 hours), which increases the start-up cost of the air separation equipment. Utility Model Content

[0003] This disclosure aims to at least partially address one of the technical problems in the related art. To this end, one object of this disclosure is to provide a heating system for air separation equipment that can complete heating before the air compressor is started, eliminating the need for heating using the air compressor unit and thus reducing the start-up cost of the air separation equipment.

[0004] The heating system for an air separation unit according to an embodiment of this disclosure includes: a device to be heated; a backup liquid nitrogen storage tank for storing liquid nitrogen; a liquid nitrogen pump connected to the backup liquid nitrogen storage tank; a heating device including a steam-type water bath vaporizer and an electric heater; the steam-type water bath vaporizer is connected to the liquid nitrogen pump for heating the liquid nitrogen supplied by the liquid nitrogen pump into nitrogen gas; the electric heater is connected to the output end of the steam-type water bath vaporizer for heating the nitrogen gas flowing out of the steam-type water bath vaporizer; a first valve connected between the output end of the steam-type water bath vaporizer and the device to be heated for connecting or disconnecting the steam-type water bath vaporizer and the device to be heated; a controller electrically connected to the liquid nitrogen pump, the electric heater and the first valve respectively; and a discharge pipeline connected to the device to be heated for discharging the nitrogen gas flowing out of the device to be heated.

[0005] In some embodiments, the liquid nitrogen pump is a variable frequency liquid nitrogen pump.

[0006] In some embodiments, the heating system further includes: a detection element for detecting the temperature of the device to be heated, and an electrical connection to a controller capable of controlling the amount of liquid nitrogen output by the variable frequency liquid nitrogen pump based on the detection result of the detection element.

[0007] In some embodiments, the heating device has multiple components, and at least two of the heating devices have their input terminals connected in parallel.

[0008] In some embodiments, the heating system further includes: a plurality of second valves, respectively disposed at the input end of the device to be heated and respectively connected to the controller, such that the controller can control the second valves to switch between an open state and a closed state; when the second valve switches to the open state according to the opening command of the controller, the nitrogen gas can flow through the second valve and enter the corresponding device to be heated; when the second valve switches to the closed state according to the closing command of the controller, it can cut off the flow of nitrogen gas to the corresponding heating system.

[0009] In some embodiments, the heating system further includes: a first pipeline connector having at least two first inlets and at least one first outlet, wherein the two first inlets are respectively connected to the steam-type water bath vaporizer and the electric heater, and one of the first outlets is used to connect to the device to be heated.

[0010] In some embodiments, the heating system further includes: a third valve, electrically connected to the controller, connected between the liquid nitrogen pump and the electric heater, for connecting or disconnecting the liquid nitrogen pump and the electric heater.

[0011] In some embodiments, the heating device includes at least one of the following: a high-pressure heat exchanger, a low-pressure heat exchanger, a subcooler, an upper column, a main condenser-evaporator, a lower column, a crude argon condenser, a crude argon column, a refined argon condenser, a refined argon column, a refined argon evaporator, and an expander.

[0012] In some embodiments, the heating system further includes: a second pipeline connector having a second inlet and at least two second outlets, the second inlet being for heated nitrogen to enter, one of the second outlets being connected to a crude argon condenser, and the nitrogen flowing out of the crude argon condenser also flowing into the crude argon tower; a third pipeline connector having a third inlet and at least two third outlets, the third inlet being connected to one of the second outlets, one of the third outlets being connected to a refined argon condenser, and the nitrogen entering the refined argon condenser also flowing into the refined argon tower and the refined argon evaporator in sequence; and a fourth pipeline connector having a fourth inlet and at least two fourth outlets, the fourth inlet being connected to one of the third outlets, one of the fourth outlets being connected to the low-pressure heat exchanger, and the nitrogen flowing out of one of the fourth outlets being able to flow into the high-pressure heat exchanger, the subcooler, the upper tower, the main condenser-evaporator, and the lower tower.

[0013] In some embodiments, the heating system further includes: a fifth pipeline connector, connected between one of the fourth outlets of the fourth pipeline connector and the high-pressure heat exchanger, subcooler, upper tower, main condenser-evaporator, and lower tower, having a fifth inlet and at least two fifth outlets; the fifth inlet is connected to the fourth outlet; one of the fifth outlets is connected to a fine argon condenser or the main condenser-evaporator; a sixth pipeline connector, having a sixth inlet and at least two sixth outlets; the sixth inlet is connected to one of the fifth outlets; one of the sixth outlets is connected to the high-pressure heat exchanger; nitrogen flowing out from one of the sixth outlets can flow into the low-pressure heat exchanger, subcooler, upper tower, main condenser-evaporator, and lower tower.

[0014] In some embodiments, the subcooler, upper column, and lower column each have multiple channels; nitrogen flowing out from one channel of the subcooler enters one channel of the upper column; a portion of the nitrogen entering one channel of the upper column flows sequentially through another channel of the subcooler and one channel of the lower column; wherein, a portion of the nitrogen flowing out from at least two channels of the upper column enters at least two channels of the subcooler, and a portion of the nitrogen flowing out from at least two channels of the subcooler enters at least two channels of the lower column; another portion of the nitrogen entering one channel of the upper column flows sequentially through the main condenser-evaporator and the lower column.

[0015] The heating system provided in this embodiment can use liquid nitrogen in the backup system to complete the heating before the air compressor is started, eliminating the need for heating with the air compressor unit. This reduces the air compressor running time during the preparation process and helps to reduce the start-up cost of the air separation equipment.

[0016] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a heating system provided in an exemplary embodiment;

[0018] Figure 2 This is a schematic diagram of the electrical connections of a heating system provided in an exemplary embodiment;

[0019] Figure 3 This is a schematic diagram of the connection of each device to be heated in a heating system provided in an exemplary embodiment.

[0020] Explanation of reference numerals in the attached diagram: 110-Backup liquid nitrogen storage tank; 120-Liquid nitrogen pump; 210-Steam-type water bath vaporizer; 220-Electric heater; 230-First valve; 300-Heating device; 311-High-pressure heat exchanger; 312-Low-pressure heat exchanger; 313-Subcooler; 314-Upper column; 315-Main condenser / evaporator; 316-Lower column; 317-Raw argon condenser; 318-Raw argon column; 319-Refined argon condenser; 320-Refined argon column; 321-Refined argon evaporator; 400-Controller. Detailed Implementation

[0021] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0022] The structure and implementation process of a heating system for an air separation unit according to an embodiment of the present disclosure are described below with reference to the accompanying drawings.

[0023] Furthermore, other components and functions of the air separation equipment in the embodiments of this disclosure are known to those skilled in the art, and will not be described in detail here to reduce redundancy.

[0024] Please refer to Figure 1 and Figure 2 This embodiment provides a heating system for an air separation unit, including: a device to be heated 300; a backup liquid nitrogen storage tank 110 for storing liquid nitrogen; a liquid nitrogen pump 120 connected to the backup liquid nitrogen storage tank 110; and a heating device including a steam-type water bath vaporizer 210 and an electric heater 220. The steam-type water bath vaporizer 210 is connected to the liquid nitrogen pump 120 and is used to heat the liquid nitrogen supplied by the liquid nitrogen pump 120 into nitrogen gas. The electric heater 220 is connected to the output end of the steam-type water bath vaporizer 210 and is used to heat the liquid nitrogen from the steam-type water bath vaporizer 210 into nitrogen gas. The nitrogen flowing out of the steam-type water bath vaporizer 210 is heated; the first valve 230 is connected between the output end of the steam-type water bath vaporizer 210 and the device to be heated 300, and is used to connect or disconnect the steam-type water bath vaporizer 210 and the device to be heated 300; the controller 400 is electrically connected to the liquid nitrogen pump 120, the electric heater 220 and the first valve 230 respectively; the discharge pipeline is connected to the device to be heated 300 and is used to discharge the nitrogen flowing out of the device to be heated 300 (the nitrogen may contain liquid).

[0025] To ensure stable operation of the air separation unit, a backup system is typically configured. This backup system includes a backup liquid nitrogen storage tank 110 for storing liquid nitrogen. The backup liquid nitrogen storage tank 110 can be connected to a liquid nitrogen pump 120 via pipeline. The liquid nitrogen pump 120 is used to extract liquid nitrogen from the backup liquid nitrogen storage tank 110 and deliver it to the heating unit. Alternatively, the liquid nitrogen pump 120 can be integrated into the backup liquid nitrogen storage tank 110 to simplify the piping.

[0026] The liquid nitrogen pump 120 can be a variable frequency liquid nitrogen pump 120, which allows the controller 400 to control the amount of gas delivered to the heating device via the variable frequency liquid nitrogen pump 120, thereby controlling the heating time of the device to be heated 300. In other examples, the amount of gas delivered to the device to be heated 300 can also be controlled by a flow control valve or the like.

[0027] The heating device is used to heat the liquid nitrogen supplied to the heating device 300. The heating device includes a steam-type water bath vaporizer 210 and an electric heater 220; the steam-type water bath vaporizer 210 is connected to the liquid nitrogen pump 120 and is used to heat the liquid nitrogen supplied by the liquid nitrogen pump 120; the electric heater 220 is connected to the output end of the steam-type water bath vaporizer 210 and is electrically connected to the controller 400, and is used to heat the nitrogen flowing out of the steam-type water bath vaporizer 210.

[0028] The steam-type water bath vaporizer 210 includes two inlet terminals, one of which is connected to the liquid nitrogen pump 120, and the other is connected to a steam pipeline. Thus, the steam entering the steam-type water bath vaporizer 210 heats the water within it, allowing the heated water to heat the liquid nitrogen passing through the heating coil. The steam can be provided by boiler waste heat or other waste heat sources.

[0029] The first valve 230 is connected between the output end of the steam-type water bath vaporizer 210 and the input end of the device to be heated 300, and is electrically connected to the controller 400. It is used to connect or disconnect the steam-type water bath vaporizer 210 and the device to be heated 300 according to the control command of the controller 400.

[0030] In some scenarios, under relatively tight time constraints, i.e., with limited pre-allocated heating time, to accelerate the heating rate, the controller 400 controls the first valve 230 to disconnect the steam-type water bath vaporizer 210 from the device to be heated 300, and the controller 400 controls the electric heater 220 to enter the working state. Thus, the liquid nitrogen is heated in the steam-type water bath vaporizer 210, and further heated by the electric heater 220. The medium, such as nitrogen gas, heated by the electric heater 220 enters the device to be heated 300 for further heating. The temperature of the medium heated by the electric heater 220 can reach 45℃.

[0031] In other scenarios, when time is relatively ample, i.e., when a considerable amount of pre-allocated heating time is available, to save energy, the controller 400 controls the first valve 230 to connect the steam-water vaporizer 210 to the device to be heated 300. In this way, the steam-water vaporizer 210 heats the liquid nitrogen, and the heated medium, such as nitrogen gas, enters the device to be heated 300 for further heating. At this time, the electric heater 220 may not be operational.

[0032] In other scenarios, part of the nitrogen entering the heating device 300 may come from the steam-type water bath vaporizer 210, and another part may come from the electric heater 220.

[0033] Optionally, a fifth valve is connected between the output of the steam bath vaporizer 210 and the input of the electric heater 220, and the fifth valve is electrically connected to the controller 400.

[0034] In some scenarios, under relatively tight time constraints, i.e., with limited pre-allocated heating time, to accelerate the heating rate, the controller 400 controls the fifth valve to connect the steam-type water bath vaporizer 210 to the electric heater 220, and the controller 400 controls the electric heater 220 to enter the working state. Thus, the liquid nitrogen is heated in the steam-type water bath vaporizer 210, and further heated by the electric heater 220. The medium, such as nitrogen gas, heated by the electric heater 220 enters the heating device 300 for further heating. The temperature of the medium heated by the electric heater 220 can reach 45℃.

[0035] In other scenarios, when there is sufficient time, i.e., when there is a large amount of reserved heating time, in order to save energy, the controller 400 controls the fifth valve to disconnect the steam water bath vaporizer 210 from the electric heater 220, and the electric heater 220 is in a non-working state. In this way, the steam water bath vaporizer 210 is used to heat the liquid nitrogen, and the medium such as nitrogen gas heated by the steam water bath vaporizer 210 enters the heating device 300 for heating.

[0036] After being heated by the heating device, the medium, such as nitrogen, enters the device to be heated 300 and is heated and dried in the device 300 before being discharged outside the heating system through the discharge pipeline. In some examples, the medium discharged from the discharge pipeline can also be recycled as needed.

[0037] The heating system provided in this embodiment includes a backup liquid nitrogen storage tank 110 for storing liquid nitrogen; a liquid nitrogen pump 120 connected to the backup liquid nitrogen storage tank 110; and a heating device including a steam-type water bath vaporizer 210 and an electric heater 220. The steam-type water bath vaporizer 210 is connected to the liquid nitrogen pump 120 for heating the liquid nitrogen supplied by the pump 120. The electric heater 220 is connected to the output end of the steam-type water bath vaporizer 210 for heating the nitrogen flowing out of the steam-type water bath vaporizer 210. A first valve 230 is connected to the output of the steam-type water bath vaporizer 210. Between the end and the device to be heated 300, it is used to connect or disconnect the steam-type water bath vaporizer 210 and the device to be heated 300; the controller 400 is electrically connected to the liquid nitrogen pump 120, the electric heater 220 and the first valve 230 respectively; the discharge pipeline is connected to the device to be heated 300 and is used to discharge the nitrogen flowing out of the device to be heated 300. Thus, in this embodiment, the liquid nitrogen in the backup system can be used to complete the heating before the air compressor is started, eliminating the process of heating with the air compressor unit, reducing the air compressor running time during the preparation process, and helping to reduce the start-up cost of the air separation equipment.

[0038] Figure 3 This is a schematic diagram of the connection of each device to be heated in a heating system provided in an exemplary embodiment; the bold lines with arrows in the figure are used to indicate the flow direction of the medium (liquid nitrogen or nitrogen gas).

[0039] Please refer to Figures 1 to 3 In some embodiments, to improve the flexibility of heating control and the effect of heating and drying, the heating device 300 has multiple devices, with at least two devices 300 connected in parallel. When the heating gas volume is small or the heating time is sufficient, the parallel devices 300 can be heated sequentially; when the heating gas volume is large or the heating time is tight, multiple parallel devices 300 can be heated simultaneously.

[0040] In some examples, the heating system further includes multiple second valves, each disposed at the input end of the device 300 to be heated and connected to a controller 400, enabling the controller 400 to control the second valves to switch between open and closed states. When a second valve switches to the open state according to an opening command from the controller 400, nitrogen gas can flow through the second valve and enter the corresponding device 300 to be heated; when a second valve switches to the closed state according to a closing command from the controller 400, it can cut off the flow of nitrogen gas to the corresponding heating system. Second valves can be separately installed in multiple parallel branches of the heating system; for example, when the devices 300 to be heated are connected in parallel, each input end of a device 300 to be heated can be equipped with a second valve.

[0041] For example, when the heating device 300 includes an expander and a cold box, the expander and cold box can be connected in parallel with the heating device. The controller 400 can control both the second valve connected to the input end of the expander and the second valve connected to the input end of the cold box to be switched to the open state, so as to heat the cold box and the expander simultaneously. The controller 400 can also control the second valve connected to the input end of the cold box to be switched to the open state and the second valve connected to the input end of the expander to be switched to the closed state to heat the cold box; then, it can control the second valve connected to the input end of the expander to be switched to the open state and the second valve connected to the input end of the cold box to be switched to the closed state to heat the expander. The cold box includes at least one heat exchanger, and the number and type of heat exchangers can be set according to actual needs.

[0042] In some embodiments, in order to simplify the piping in the heating system, the heating system further includes a first pipe connector; the first pipe connector has at least two first inlets and at least one first outlet, wherein the two first inlets are respectively connected to a steam-type water bath vaporizer 210 and an electric heater 220, and one of the first outlets is used to connect to the device to be heated 300.

[0043] When time is relatively tight, the controller 400 controls the first valve 230 to connect the steam-type water bath vaporizer 210 to the electric heater 220, and the controller 400 controls the electric heater 220 to enter the working state. In this way, the steam-type water bath vaporizer 210 heats the liquid nitrogen, and the electric heater 220 further heats it. The medium, such as nitrogen gas, heated by the electric heater 220 enters the heating device 300 through the first pipeline connection for further heating. When time is relatively sufficient, the controller 400 controls the first valve 230 to disconnect the steam-type water bath vaporizer 210 from the electric heater 220, and the electric heater 220 is in a non-working state. In this way, the steam-type water bath vaporizer 210 heats the liquid nitrogen, and the medium, such as nitrogen gas, heated by the steam-type water bath vaporizer 210 enters the heating device 300 through the first pipeline connection for further heating.

[0044] In some embodiments, to improve the flexibility of controlling the heating system, the heating system further includes a third valve; the third valve is electrically connected to the controller 400 and is connected between the liquid nitrogen pump 120 and the electric heater 220, for turning the liquid nitrogen pump 120 and the electric heater 220 on or off. Thus, in scenarios where there is no residual heat to provide to the steam-type water bath vaporizer 210, the controller 400 can control the third valve to turn the liquid nitrogen pump 120 on and off the electric heater 220, allowing the liquid nitrogen supplied by the liquid nitrogen pump 120 to directly enter the electric heater 220 for heating.

[0045] Optionally, a fourth valve can be connected between the steam-type water bath vaporizer 210 and the liquid nitrogen pump 120. The fourth valve is electrically connected to the controller 400. In scenarios where there is no residual heat to be provided to the steam-type water bath vaporizer 210, the controller 400 can control the first valve 230 and the fourth valve to disconnect the corresponding passages to ensure that the liquid nitrogen provided by the liquid nitrogen pump 120 can enter the electric heater 220.

[0046] In some embodiments, the heating device 300 includes at least one of the following: a high-pressure heat exchanger 311, a low-pressure heat exchanger 312, a subcooler 313, an upper column 314, a main condenser-evaporator 315, a lower column 316, a crude argon condenser 317, a crude argon column 318, a refined argon condenser 319, a refined argon column 320, a refined argon evaporator 321, and an expander.

[0047] The specific number and type of the heating devices 300 can be set according to actual needs, and the heating devices 300 can include any combination of one or more of the above. For example, the heating devices 300 can include a fine argon tower 320, a main condenser-evaporator 315, and an expander. Another example is that the heating devices 300 can include a high-pressure heat exchanger 311, a low-pressure heat exchanger 312, a subcooler 313, an upper tower 314, a main condenser-evaporator 315, a lower tower 316, a crude argon condenser 317, a crude argon tower 318, a fine argon condenser 319, a fine argon tower 320, a fine argon evaporator 321, and an expander; the following explanation uses this as an example.

[0048] In some examples, the heating system may include multiple pipe connections with at least three ports, which simplifies the piping within the heating system. Alternatively, pipe connections with adapter or multi-port functions can be used to utilize existing air intake lines in the air separation unit, providing space and guidance for nitrogen flow, thereby reducing the need for additional piping and lowering costs. Specific configurations can be tailored to actual needs.

[0049] The heating system may include a second pipe connection. The second pipe connection has a second inlet and at least two second outlets, the second inlet being for the intake of heated nitrogen, and one of the second outlets being for connection to the crude argon condenser 317 and the crude argon tower 318.

[0050] The nitrogen gas flowing out from the second outlet can sequentially pass through the crude argon condenser 317 and the crude argon tower 318, and then be discharged from the exhaust pipe; alternatively, the nitrogen gas flowing out from the second outlet can also enter the crude argon condenser 317 and the crude argon tower 318 through parallel branches, and then be discharged from the exhaust pipe. The remaining second outlets can be connected to other devices 300 to be heated.

[0051] The heating system also includes a third piping connection. The third piping connection has a third inlet and at least two third outlets. The third inlet is connected to one of the second outlets, and one of the third outlets is connected to the argon condenser 319, the argon tower 320, and the argon evaporator 321. The remaining third outlets can be connected to other devices 300 to be heated.

[0052] Nitrogen gas flowing out from the third outlet can sequentially pass through the argon condenser 319, the argon tower 320, and the argon evaporator 321, and be discharged from the exhaust pipe; or, nitrogen gas flowing out from the third outlet can also enter the argon condenser 319, the argon tower 320, and the argon evaporator 321 respectively through parallel branches; or, depending on the requirements, two of them can be connected in series and then connected in parallel with another. For example, nitrogen gas flowing out from the third outlet enters the seventh pipeline connector, which has at least two seventh outlets. Nitrogen gas flowing out from one of the seventh outlets enters the argon condenser 319, and nitrogen gas flowing out from the other seventh outlet sequentially enters the argon tower 320 and the argon evaporator 321.

[0053] The heating system also includes a fourth pipe connection. This fourth pipe connection has a fourth inlet and at least two fourth outlets. The fourth inlet is connected to one of the third outlets, one of the fourth outlets is connected to the high-pressure heat exchanger 311, the subcooler 313, the upper tower 314, the main condenser-evaporator 315, and the lower tower 316, and one of the fourth outlets is connected to the low-pressure heat exchanger 312. Nitrogen gas flows into the low-pressure heat exchanger 312 from the fourth outlet and can then be discharged through the exhaust pipe, or it can enter other devices 300 to be heated as needed.

[0054] The heating system also includes a fifth pipe connection. The fifth pipe connection is connected between one of the fourth outlets of the fourth pipe connection and the high-pressure heat exchanger 311, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316, so that the nitrogen gas flowing out from the fourth outlet flows through the fifth pipe connection to the high-pressure heat exchanger 311, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316.

[0055] The fifth pipeline connection has a fifth inlet and at least two fifth outlets; the fifth inlet is connected to one of the fourth outlets of the fourth pipeline connection; one of the fifth outlets is connected to the argon condenser 319, the main condenser evaporator 315, and the lower tower 316.

[0056] The heating system also includes a sixth pipe connection. The sixth pipe connection has a sixth inlet and at least two sixth outlets; the sixth inlet is connected to one of the fifth outlets; one of the sixth outlets is connected to the high-pressure heat exchanger 311; and one of the sixth outlets is connected to the low-pressure heat exchanger 312, the subcooler 313, the upper tower 314, the main condenser-evaporator 315, and the lower tower 316.

[0057] The low-pressure heat exchanger 312, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316 connected to the sixth outlet can be connected in series; or, the low-pressure heat exchanger 312, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316 connected to the sixth outlet can be connected in parallel; or, at least two of the low-pressure heat exchanger 312, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316 connected to the sixth outlet can be connected in parallel, and at least two can be connected in series.

[0058] The heating system also includes an eighth pipe connection, which connects the high-pressure heat exchanger 311 to the sixth outlet of the sixth pipe connection. The eighth pipe connection has an eighth inlet and at least two eighth outlets; the eighth inlet is connected to one of the sixth outlets; one of the eighth outlets is connected to multiple channels in the high-pressure heat exchanger 311. Nitrogen flowing out of one of the eighth outlets can sequentially pass through the high-pressure heat exchanger 311, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316. The high-pressure heat exchanger 311, subcooler 313, upper tower 314, main condenser-evaporator 315, and lower tower 316 can be connected in series. Nitrogen flowing out of the remaining eighth outlets can pass through the high-pressure heat exchanger 311 and be discharged from the exhaust pipe.

[0059] Nitrogen gas flowing out of the high-pressure heat exchanger 311 and the low-pressure heat exchanger 312 can enter the subcooler 313 through the ninth pipeline connection, and then flow sequentially through the upper column 314, the main condenser-evaporator 315, and the lower column 316. The ninth pipeline connection has at least two ninth inlets and at least one ninth outlet; the two ninth inlets are respectively connected to the output end of the high-pressure heat exchanger 311 and the output end of the low-pressure heat exchanger 312, and the ninth outlet can be connected to the subcooler 313, and the nitrogen gas flowing out of the subcooler 313 then flows sequentially through the upper column 314, the main condenser-evaporator 315, and the lower column 316.

[0060] Subcooler 313, upper column 314, and lower column 316 each have multiple channels; nitrogen gas flowing out from one channel of subcooler 313 enters one channel of upper column 314; a portion of the nitrogen gas entering one channel of upper column 314 flows sequentially through another channel of subcooler 313 and one channel of lower column 316; wherein, a portion of the nitrogen gas flowing out from at least two channels of upper column 314 enters at least two channels of subcooler 313, and a portion of the nitrogen gas flowing out from at least two channels of subcooler 313 enters at least two channels of lower column 316; another portion of the nitrogen gas entering one channel of upper column 314 flows sequentially through main condenser-evaporator 315 and lower column 316.

[0061] For ease of description, the channels in the upper column 314, including the first, second, third, and fourth channels, will be used as an example. Nitrogen gas flowing from the subcooler 313 enters the first channel of the upper column 314. A portion of the nitrogen gas entering the first channel flows through the subcooler 313 and the lower column 316 and is discharged through the exhaust pipe; another portion of the nitrogen gas entering the first channel flows into the second channel of the upper column 314. A portion of the nitrogen gas entering the second channel flows through the subcooler 313 and the lower column 316 and is discharged through the exhaust pipe; the nitrogen gas entering the second channel... Another portion of the nitrogen flows into the third channel of the upper tower 314; a portion of the nitrogen entering the third channel flows through the cooler 313 and the lower tower 316 and is discharged from the exhaust pipe, while another portion of the nitrogen entering the third channel flows into the fourth channel of the upper tower 314; the nitrogen entering the fourth channel is discharged from the exhaust pipe, or the nitrogen entering the fourth channel flows through the remaining channels of the upper tower 314 in sequence and is discharged from the exhaust pipe, or the nitrogen entering the fourth channel flows through the remaining channels of the upper tower 314 in sequence and enters the main condenser-evaporator 315 and is then discharged from the exhaust pipe.

[0062] The lower tower 316 may also include multiple channels, and some of the nitrogen flowing out from the multiple channels of the upper tower 314 can flow into different channels of the lower tower 316. Taking the lower tower 316 as an example, which includes a fifth, sixth, and seventh channel, some of the nitrogen flowing out from three channels of the upper tower 314 can enter the fifth, sixth, and seventh channels respectively; the nitrogen entering the fifth channel also flows through the sixth and seventh channels and is then discharged from the exhaust pipe; the nitrogen entering the sixth channel also flows through the seventh channel and is then discharged from the exhaust pipe; and the nitrogen entering the seventh channel is discharged from the exhaust pipe.

[0063] The heating system also includes a tenth pipe connection, which connects to the eighth outlet of the eighth pipe connection and the high-pressure heat exchanger 311. The tenth pipe connection has a tenth inlet and at least two tenth outlets; the tenth inlet is connected to one of the eighth outlets; each tenth outlet is connected to multiple channels in the high-pressure heat exchanger 311 and then discharged from the outlet pipe.

[0064] In this embodiment, by employing multiple pipeline connectors and rationally configuring their installation positions, multiple devices 300 to be heated can be connected in parallel. This improves the heating and drying effect of the devices 300 and shortens the heating time. For example, the time from hot start-up of the air separation unit to producing qualified product gas is approximately 48 hours. Heating multiple parallel devices 300 sequentially takes approximately 48 hours, and heating all parallel devices 300 simultaneously takes approximately 24 hours. Therefore, this embodiment shortens the heating time. In practical implementation, a backup system can be started 96 to 72 hours before the planned gas consumption of the subsequent system, and the heating can be completed 48 hours before the planned gas consumption of the subsequent system.

[0065] In some embodiments, the heating system further includes a detection element. The detection element is used to detect the temperature of the device 300 to be heated and is electrically connected to a controller 400 that can control the amount of liquid nitrogen output by the variable frequency liquid nitrogen pump 120 based on the detection result of the detection element. For example, the detection element may include a temperature sensor; each device 300 to be heated may be provided with a temperature sensor.

[0066] In some scenarios, when the controller 400 determines that the actual temperature of the device to be heated 300 has reached the set value based on the detection results of the temperature sensor, the controller 400 controls the liquid nitrogen pump 120 to stop outputting liquid nitrogen, the controller 400 controls the electric heater 220 to stop working, and the controller 400 can also control the second valve to disconnect the corresponding passage.

[0067] In some scenarios, when the controller 400 determines the actual temperature of the device to be heated 300 based on the detection results of the temperature sensor, and determines that the actual temperature rise rate of the device to be heated 300 is lower than expected, the controller 400 can control the liquid nitrogen pump 120 to increase the output.

[0068] In this embodiment, a pipeline is drawn from the backup liquid nitrogen storage tank 110 and connected to a heating device, which in turn connects to multiple devices 300 to be heated. Before starting up, the backup system is started, and the liquid nitrogen is vaporized using the heating device to heat the distillation column, argon column, high and low pressure heat exchanger 312, etc. in the air separation unit to the dew point of qualified conditions. Then the air compressor unit is started, which greatly reduces the running time of the air compressor unit during the preparation before the air separation unit starts up, and can save a lot of high-pressure steam.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0070] Furthermore, the terms "first," "second," etc., used in the embodiments of this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this disclosure can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this disclosure, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0071] In this disclosure, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing," etc., appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific implementation.

[0072] Although embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A heating system for an air separation unit, characterized in that, include: Heating device; Backup liquid nitrogen storage tank for storing liquid nitrogen; A liquid nitrogen pump is connected to the backup liquid nitrogen storage tank; A heating device includes a steam-type water bath vaporizer and an electric heater; the steam-type water bath vaporizer is connected to the liquid nitrogen pump and is used to heat the liquid nitrogen supplied by the liquid nitrogen pump into nitrogen gas; the electric heater is connected to the output end of the steam-type water bath vaporizer and is used to heat the nitrogen gas flowing out of the steam-type water bath vaporizer. The first valve is connected between the output end of the steam-type water bath vaporizer and the device to be heated, and is used to connect or disconnect the steam-type water bath vaporizer and the device to be heated. The controller is electrically connected to the liquid nitrogen pump, the electric heater, and the first valve, respectively. An exhaust pipe, connected to the device to be heated, is used to discharge nitrogen gas flowing out of the device to be heated.

2. The heating system according to claim 1, characterized in that, The liquid nitrogen pump is a variable frequency liquid nitrogen pump.

3. The heating system according to claim 2, characterized in that, Also includes: A detection element for detecting the temperature of the device to be heated is electrically connected to a controller that controls the amount of liquid nitrogen output by the variable frequency liquid nitrogen pump based on the detection result of the detection element.

4. The heating system according to claim 1, characterized in that, The heating device has multiple components, and at least two of the heating devices have their input terminals connected in parallel.

5. The heating system according to claim 4, characterized in that, Also includes: Multiple second valves are respectively installed at the input end of the device to be heated and are respectively connected to the controller, so that the controller can control the second valves to switch between open and closed states.

6. The heating system according to claim 1, characterized in that, Also includes: The first pipeline connector has at least two first inlets and at least one first outlet, wherein the two first inlets are respectively connected to the steam-type water bath vaporizer and the electric heater, and one of the first outlets is used to connect to the device to be heated. And / or, The third valve, electrically connected to the controller, is connected between the liquid nitrogen pump and the electric heater, and is used to connect or disconnect the liquid nitrogen pump and the electric heater.

7. The heating system according to claim 1, characterized in that, The heating device includes at least one of the following: a high-pressure heat exchanger, a low-pressure heat exchanger, a subcooler, an upper tower, a main condenser-evaporator, a lower tower, a crude argon condenser, a crude argon tower, a refined argon condenser, a refined argon tower, a refined argon evaporator, and an expander.

8. The heating system according to claim 7, characterized in that, Also includes: The second pipeline connection has a second inlet and at least two second outlets. The second inlet is used to allow heated nitrogen to enter, and one of the second outlets is used to connect to the crude argon condenser. Nitrogen flowing out of the crude argon condenser also flows into the crude argon tower connection. The third pipeline connector has a third inlet and at least two third outlets. The third inlet is connected to one of the second outlets, and one of the third outlets is connected to a fine argon condenser. The nitrogen entering the fine argon condenser also flows sequentially into the fine argon tower and the fine argon evaporator. The fourth pipeline connection has a fourth inlet and at least two fourth outlets. The fourth inlet is connected to one of the third outlets, and one of the fourth outlets is connected to the low-pressure heat exchanger. Nitrogen flowing out from one of the fourth outlets can flow into the high-pressure heat exchanger, subcooler, upper tower, main condenser-evaporator, and lower tower.

9. The heating system according to claim 8, characterized in that, Also includes: A fifth pipeline connector is connected between one of the fourth outlets of the fourth pipeline connector and the high-pressure heat exchanger, subcooler, upper tower, main condenser-evaporator, and lower tower, and has a fifth inlet and at least two fifth outlets; the fifth inlet is connected to the fourth outlet; one of the fifth outlets is connected to the argon condenser or the main condenser-evaporator. The sixth pipeline connection has a sixth inlet and at least two sixth outlets; the sixth inlet is connected to one of the fifth outlets; one of the sixth outlets is connected to the high-pressure heat exchanger; nitrogen flowing out from one of the sixth outlets can flow into the low-pressure heat exchanger, subcooler, upper tower, main condenser-evaporator, and lower tower.

10. The heating system according to claim 8, characterized in that, The subcooler, upper column, and lower column each have multiple channels; Nitrogen gas flowing out from one of the channels of the subcooler enters one of the channels of the upper column; A portion of the nitrogen gas entering one of the channels of the upper column flows sequentially through another channel of the subcooler and one of the channels of the lower column; wherein, a portion of the nitrogen gas flowing out from at least two channels of the upper column enters at least two channels of the subcooler, and a portion of the nitrogen gas flowing out from at least two channels of the subcooler enters at least two channels of the lower column. Another portion of the nitrogen gas entering one of the channels of the upper tower flows sequentially through the main condenser-evaporator and the lower tower.

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