Backup gas supply device and air separation gas supply method

Abstract

The present application provides a kind of backup gas supply equipment and air separation gas supply method.Backup gas supply equipment is used to assist air separation equipment gas supply.In which,steam vaporizer is set to the downstream of backflow position on delivery pipeline.Delivery pipeline has gas supply pipe section and recovery pipe section leading to user end and air separation equipment respectively downstream of steam vaporizer.Backup gas supply equipment is set to be able to switch between two modes by switching assembly.Switching assembly is set so that, in two modes, the operating power of backup pump, the vaporization flow of vaporization stream passing through steam vaporizer through backup pump, and the steam flow of hot steam leading to steam vaporizer are all different.The above-mentioned backup gas supply equipment and air separation gas supply method can realize fast start while avoiding product element loss.

Description

Technical Field

[0001] This invention belongs to the field of air separation and relates to an air separation gas supply method, and in particular, to a backup gas supply device. Background Technology

[0002] When using air separation equipment for gas supply, it is often equipped with backup gas supply equipment including storage tanks, backup pumps, and backup vaporizers. This prevents a disruption in gas supply to users should the air separation equipment malfunction and fail to provide normal gas supply. During normal operation, the backup pump can be in a cold standby state. When the air separation equipment trips, the backup pump can start immediately, delivering liquid to the backup vaporizer, where it is vaporized and supplied to users as a gaseous product.

[0003] Chinese invention patent CN111566425B discloses an air separation gas supply system. During normal operation of the air separation unit, the system draws cryogenic liquid from the storage tank, which is then pressurized by a backup pump in a cold standby state. A portion of the cryogenic liquid is then depressurized and delivered to the user via a product supply pipeline. In temporary operating conditions where the air separation unit stops or operates at a slower speed, the cryogenic liquid drawn from the storage tank is pressurized by a high-speed backup pump and then delivered to the user via another product supply pipeline.

[0004] However, in practice, there may not be users who need to receive low-pressure air from the aforementioned product supply pipeline. In such cases, how to achieve rapid start-up while avoiding product element loss is a problem that needs to be considered. Summary of the Invention

[0005] The purpose of this invention is to provide a device or method that can achieve rapid startup while avoiding loss of product elements.

[0006] This invention provides a backup gas supply device for assisting air separation equipment in gas supply. The backup gas supply device includes a storage tank, a delivery pipeline system, and a switching assembly. The delivery pipeline system includes a delivery line that delivers fluid downstream from the storage tank, and a backup pump is disposed on the delivery pipeline. The delivery pipeline system also includes a return line configured to return a portion of the pumped liquid from the backup pump back to the storage tank from a return position downstream of the backup pump on the delivery pipeline. A steam vaporizer is disposed downstream of the return position on the delivery pipeline. Downstream of the steam vaporizer, the delivery pipeline has a supply section and a recovery section leading to the user end and the air separation equipment, respectively. The supply section and the recovery section have the same inlet. The backup gas supply device is configured to switch between two modes via the switching assembly. The switching assembly is configured such that, in the two modes, the operating power of the backup pump, the vaporization flow rate of the vaporized stream passing through the steam vaporizer from the backup pump, and the steam flow rate of the hot steam leading to the steam vaporizer are all different.

[0007] In one embodiment, the storage tank is used to store liquid oxygen. The air separation unit includes a low-pressure tower and a high-pressure tower operating at lower and higher pressures, a main evaporator connecting the low-pressure tower and the high-pressure tower via a heat transfer relationship, and a main heat exchanger that cools the feed air before sending it to the high-pressure tower. The outlet of the recovery section is located at the main evaporator, and the recovery section passes through the main heat exchanger before reaching the main evaporator.

[0008] In one embodiment, the switching component includes a line regulating device. The line regulating device is configured to regulate the vaporization flow rate and the steam flow rate.

[0009] In one embodiment, the pipeline regulating device includes two switching valves respectively disposed in the gas supply section and the gas recovery section. The pipeline regulating device also includes a return regulating valve disposed in the return pipeline.

[0010] In one embodiment, the air separation unit further includes gas delivery lines and liquid delivery lines that supply gas to users and output liquid products to storage tanks, respectively. The outlet of the gas delivery line is located downstream of the corresponding switching valve of the gas supply line section.

[0011] In one embodiment, the delivery pipeline includes two parallel vaporization regulating sections between the return position and the steam vaporizer. The pipeline regulating device includes two vaporization regulating valves disposed on the two vaporization regulating sections. The backup gas supply equipment includes a steam pipeline for delivering hot steam, the steam pipeline including two parallel steam regulating sections, and the pipeline regulating device further including two steam regulating valves disposed on the two steam regulating sections.

[0012] In one implementation, the two vaporization regulating valves are of different specifications. The two steam regulating valves are of different specifications.

[0013] In one embodiment, the flow coefficients of the two vaporization control valves differ by more than 20 times. The flow coefficients of the two steam control valves differ by more than 20 times.

[0014] In one embodiment, the switching assembly further includes a detector and a controller. The detector is configured to detect the gas supply status of the air separation unit and issue a detection signal. The controller is configured to issue a switching signal based on the detector's detection signal. The switching signal includes a control signal that selectively switches two vaporization regulating valves, selectively switches two steam regulating valves, selectively switches two switching valves, switches a reflux regulating valve, and adjusts the operating power of the backup pump.

[0015] This invention also provides an air separation gas supply method, employing an air separation unit for gas supply. Under normal operating conditions with sufficient gas supply from the air separation unit, gaseous products are supplied to the user end through the air separation unit. Simultaneously, a backup pump draws pumped liquid from a storage tank at a lower load, and most of the pumped liquid is returned to the storage tank as return liquid through a return pipeline, instead of being sent to the steam vaporizer; a small portion of the pumped liquid is sent as a vaporization stream to the steam vaporizer for vaporization, and then sent to the air separation unit for recovery. Under abnormal operating conditions with insufficient gas supply from the air separation unit, the backup pump is increased from a lower load to a higher load, drawing pumped liquid from the storage tank, and the steam flow rate of the hot steam passing through the steam vaporizer is increased. After all the pumped liquid is vaporized by the steam vaporizer, it is supplied to the user end as a gaseous product.

[0016] In one implementation, under normal operating conditions, the vaporized stream accounts for less than 1 / 10 of the total volume of pumped liquid extracted by the backup pump. The lower load is the idle load of the backup pump, and the higher load is the design load of the backup pump.

[0017] In one embodiment, on the pipeline that transports pumped liquid from the storage tank to the steam vaporizer, two parallel vaporization regulating pipe sections are installed between the return point of the return pipeline and the steam vaporizer, and a vaporization regulating valve is installed on each of the two vaporization regulating pipe sections. By selectively switching the two vaporization regulating valves, under normal operating conditions, a small portion of the pumped liquid is sent to the steam vaporizer for vaporization through the vaporization regulating pipe section with a relatively smaller designed flow rate; while under abnormal operating conditions, the entire pumped liquid is sent to the steam vaporizer for vaporization through the other vaporization regulating pipe section with a relatively larger designed flow rate.

[0018] In one embodiment, two parallel steam regulating pipe sections are provided on the steam pipeline transporting hot steam, and steam regulating valves are respectively installed on the two steam regulating pipe sections. When the two vaporization regulating valves are selectively switched on and off, the two steam regulating valves are also selectively switched on and off, so that the steam flow rate under normal operating conditions is lower than that under abnormal operating conditions.

[0019] In one embodiment, two vaporization regulating valves with flow coefficients differing by more than 20 times are used. Alternatively, two steam regulating valves with flow coefficients differing by more than 20 times are used.

[0020] When the aforementioned backup gas supply equipment is used, the air separation gas supply method described above can be implemented, thus enabling mode switching based on whether the air separation unit has sufficient gas supply. This involves adjusting parameters such as the backup pump's operating power, vaporization flow rate, and steam flow rate. Specifically, when the air separation unit is operating normally and thus has sufficient gas supply, while the air separation unit supplies gas products to the user, the backup pump can, for example, coast, drawing liquid from the storage tank. Furthermore, through the return pipeline, most of the pumped liquid can be returned to the storage tank before the steam vaporizer; only a small portion of the pumped liquid is sent as a vaporization stream to the steam vaporizer for vaporization, and then sent to the air separation unit for recovery. In the event of insufficient gas supply, such as when the air separation unit trips and completely stops supplying gas, the backup pump can quickly increase from coasting to, for example, the design load, drawing pumped liquid from the storage tank, and, for example, all of the pumped liquid is vaporized via the steam vaporizer, thus continuing to supply the required gas products to the user. Simultaneously, the steam flow rate of the hot steam passing through the steam vaporizer is increased to provide sufficient heat for vaporization. In this way, while achieving rapid startup of the backup system, product elements are recovered into the air separation unit, thus avoiding product element loss. Furthermore, under normal operating conditions, the stream recovered from the storage tank into the air separation unit represents only a small portion of the total liquid volume pumped by the backup pump, and the backup pump is only in a coasting state at this time, so the original total volume is already very small. Therefore, the amount of liquid recovered from the storage tank into the air separation unit is extremely small and has virtually no impact on the normal operation of the air separation unit.

[0021] Moreover, by using a steam vaporizer, it is easy to put the vaporizer and the backup pump into a low-load operation preparation state, thus enabling rapid start-up and meeting special user needs.

[0022] Furthermore, through pipeline design and the layout and configuration of pipeline components, mode switching can be easily achieved, ensuring reliable operation and low cost. Attached Figure Description

[0023] The advantages and spirit of the present invention can be further understood through the following detailed description and accompanying drawings.

[0024] Figure 1 This is a schematic diagram of an exemplary backup gas supply device according to an embodiment of the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, it should be understood that the present invention is not limited to the embodiments described below, and the technical concept of the present invention can be implemented in combination with other known technologies or functions, or with other technologies similar to those known technologies.

[0026] For example, if the first feature described subsequently in the specification is formed above or on the second feature, this can include embodiments where the first and second features are formed by direct connection, or embodiments where an additional feature is formed between the first and second features, so that the first and second features are not directly connected. Furthermore, when the first element is described in a manner connected or combined with the second element, the description includes embodiments where the first and second elements are directly connected or combined with each other, as well as embodiments where one or more other intervening elements are incorporated to indirectly connect or combine the first and second elements with each other.

[0027] The terms "first" and "second" are used for descriptive purposes only and do not refer to a limitation on time sequence, quantity, or importance. They should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, but are merely used to distinguish one technical feature from another in this technical solution. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "multiple" means two or more (i.e., more than two), unless otherwise explicitly specified. Similarly, qualifiers such as "one" appearing in the text do not refer to a limitation on quantity, but describe technical features not previously mentioned. Likewise, unless a noun is modified by a specific quantifier, the text should be considered to include both singular and plural forms; the technical solution may include either a singular or plural number of that technical feature. Similarly, modifiers such as "approximately," "about," or "around" preceding numerals generally include the number itself, and their specific meaning should be understood in conjunction with the context.

[0028] As mentioned earlier, the backup pump can be operated at low speed during normal operation of the air separation unit for rapid start-up. This shortens the start-up time of the backup pump, thus reducing the impact of air separation unit shutdown on downstream users. In the methods mentioned in the background art, another user is used to receive the low-pressure gas product converted from excess liquid pumped by the backup pump.

[0029] However, in practice, during normal operation of an air separation unit, there may not be a user needing to convert pumped liquid, such as low-pressure oxygen, into a low-pressure gaseous product from a low-speed backup pump. In this case, directly discharging the gas vaporized in the backup vaporizer would result in the loss of elements such as oxygen molecules. Therefore, a solution is needed that enables rapid start-up while avoiding the loss of product elements such as oxygen, and has broader applicability.

[0030] The inventors believe that it is possible to vaporize the pumped liquid drawn from the low-speed backup pump and recover it into the air separation unit. Vaporization followed by recovery improves recovery efficiency. More importantly, this keeps the backup vaporizer in a ready state, allowing it to start quickly when needed, further significantly reducing startup time.

[0031] However, how to minimize disruption to the normal operation of the air separation unit is a problem that requires further consideration. The inventors believe it's necessary to control the gas flow rate recovered to the air separation unit. However, when using the backup storage tank for gas supply, a very high gas flow rate is required. A further problem arises: the control valves struggle to adapt to such significant flow rate changes. Furthermore, the inventors believe that the flow rate of the corresponding steam vaporizer also needs to be able to vary significantly to accommodate normal and abnormal switching.

[0032] The exemplary backup gas supply device 10 provided by the present invention, such as Figure 1 As shown. The backup gas supply device 10 is used to supply gas to the auxiliary air separation unit 80. It is understood that the accompanying drawings are for illustrative purposes only and are not necessarily drawn to scale, and should not be construed as limiting the scope of protection of the present invention.

[0033] The backup gas supply equipment 10 includes a storage tank 1, a delivery piping system 2, and a switching assembly 3. The delivery piping system 2 includes a delivery line 20 that delivers fluid downstream from the storage tank 1. A backup pump 4 is disposed on the delivery line 20. The delivery piping system 2 also includes a return line 26. The return line 26 is configured to return a portion of the pumped liquid q0 from the backup pump 4 to the storage tank 1 from a return position P1 downstream of the backup pump 4 on the delivery line 20.

[0034] The steam vaporizer 5 is located downstream of the return position P1 on the delivery pipeline 20. Downstream of the steam vaporizer 5, the delivery pipeline 20 has a gas supply section 27 and a recovery section 28 leading to the user terminal 70 and the air separation unit 80, respectively. The gas supply section 27 and the recovery section 28 have the same inlet P7.

[0035] The steam vaporizer 5 is a vaporizer that uses heat from hot steam s6 to vaporize a cryogenic liquid. Hot steam s6 is typically waste heat from the user's factory, with a temperature generally above 80°C, such as 100°C. Furthermore, the text uses "upstream" and "downstream" to describe relative locations; these terms are relative to the flow direction of the corresponding streams in the pipeline.

[0036] The backup gas supply device 10 is configured to switch between two modes, M1 and M2, via the switching component 3. The switching component 3 is configured such that, in both modes M1 and M2, the operating power w4 of the backup pump 4, the vaporization flow rate f5 of the vaporized stream s5 passing through the steam vaporizer 5 via the backup pump 4, and the steam flow rate f6 of the hot steam s6 leading to the steam vaporizer 5 are all different. That is, the switching component 3 can change at least these three parameters—operating power w4, vaporization flow rate f5, and steam flow rate f6—thereby achieving the switching between modes M1 and M2.

[0037] When the aforementioned backup gas supply device 10 is used, mode switching can be achieved, for example, based on whether the air separation unit 80 has sufficient gas supply. Mode switching can be achieved by adjusting parameters such as the operating power w4, vaporization flow rate f5, and steam flow rate f6 of the backup pump 4. Specifically, while the air separation unit 80 is operating normally and supplying sufficient gaseous product g0 to the user end 70, the backup pump 4 can, for example, coast to draw pumped liquid q0 from the storage tank 1. Through the return line 26, most of the pumped liquid q0 (e.g., 80-90%) can be returned to the storage tank 1 as return liquid q6 before the steam vaporizer 5 (i.e., not sent to the steam vaporizer 5 but sent to the storage tank 1), and only a small portion of the pumped liquid q0 (e.g., 10-20%) is sent as vaporization stream s5 to the steam vaporizer 5 for vaporization, and then sent to the air separation unit 80 for recovery. In the event that the air separation unit 80 trips and is temporarily unable to supply gas, the backup pump 4 can quickly increase from coasting load to, for example, design load, drawing pumping liquid q0 from storage tank 1 and vaporizing, for example, all of the pumping liquid q0 via steam vaporizer 5, thus continuing to supply the required gaseous product g0 to the user end 70. Simultaneously, the steam flow rate f6 of the hot steam s6 passing through steam vaporizer 5 is increased to provide sufficient heat for vaporization. In this way, while achieving rapid backup startup, product elements such as oxygen are recovered into the air separation unit 80, thus avoiding the loss of product elements such as oxygen.

[0038] Under normal operating conditions, the stream that exits from storage tank 1 and is recovered into the air separation unit 80 accounts for only a small portion of the total pumped liquid q0 pumped by backup pump 4. Moreover, backup pump 4 is only in coasting mode at this time, so the original total volume is already very small. Therefore, the amount of liquid recovered from storage tank 1 into the air separation unit 80 is extremely small and has virtually no impact on the normal operation of the air separation unit 80.

[0039] Furthermore, the special selection of the aforementioned steam vaporizer 5 allows the backup vaporizer to easily enter a low-load operation preparation state together with the backup pump 4, thereby achieving ultra-fast start-up and meeting the user's special needs. This will be described in more detail later; the start-up time of a single backup pump 4 in a low-load operation preparation state can even be further reduced from 60 seconds to 30 seconds.

[0040] It is understandable that "most" and "small part" refer to 50% or more and 50% or less of the total, respectively. In particular, the sum of the two can constitute 100% of the total. Furthermore, "most" means not less than 80%, while "small part" means not more than 20%. Even further, "most" means not less than 90%, while "small part" means not more than 10%. In addition, the above-mentioned backup gas supply equipment 10 can switch between two modes, which only indicates that the backup gas supply equipment 10 has at least two modes, and does not exclude the possibility of having other different third modes, fourth modes, etc.

[0041] like Figure 1 As shown, the switching component 3 may include a pipeline regulating device 30. The pipeline regulating device 30 is configured to adjust the vaporization flow rate f5 and the steam flow rate f6. For example... Figure 1 As shown, the pipeline regulating device 30 may include two switching valves 37 and 38 respectively located in the gas supply section 27 and the recovery section 28, which may be referred to as the backup switching valve 37 and the recovery switching valve 38, respectively. The pipeline regulating device 30 may include a return regulating valve 36 located in the return pipeline 26. The above arrangement can easily achieve mode switching. Incidentally, the backup pump 4 can typically adjust its own operating power w4. The backup pump 4 may be a power-adjustable (or load-adjustable, or speed-adjustable) liquid pump, especially one with an idler mode. Taking speed as an example, the speed in idler mode may be, for example, 1 / 3 of the speed in design load mode.

[0042] like Figure 1 As shown, the air separation unit 80 also has a gas supply line 87 and a liquid supply line 81 that supply gas to the user terminal 70 (that is, supply gas product g0) and output liquid product q1 to the storage tank 1, respectively.

[0043] The outlet P8 of the gas transmission line 87 is located downstream of the corresponding switching valve (i.e., the backup switching valve 37) of the gas supply line section 27. That is, the gas transmission line 87 connects to the gas supply line section 27 at a position between the backup switching valve 37 and the user end 70. This arrangement facilitates seamless switching between normal and backup gas supply.

[0044] Figure 1In this system, storage tank 1 is used to store liquid oxygen, commonly referred to as LOX. The air separation unit 80 includes a low-pressure tower K2 and a high-pressure tower K1, with relatively low and high operating pressures, respectively. The air separation unit 80 also includes a main evaporator E2 that connects the low-pressure tower K2 and the high-pressure tower K1 via heat transfer, and a main heat exchanger E1 that cools the feed air a0 before sending it to the high-pressure tower K1. For example, the operating pressure of the low-pressure tower K2 is, for example, 1 bar to 2 bar, and the pressure of the main evaporator E2 is approximately the same as that of the low-pressure tower K2. The operating pressure of the high-pressure tower K1 is 4 bar to 6 bar, for example, 5 bar. "Connected via heat transfer" means that the main evaporator E2 allows the streams in the high-pressure tower K1 and the low-pressure tower K2 to exchange heat with each other.

[0045] The outlet u8 of the recovery pipe section 28 is located at the main evaporator E2, and the recovery pipe section 28 passes through the main heat exchanger E1 before entering the main evaporator E2. In this way, oxygen is pre-cooled in the main heat exchanger E1 before entering the main evaporator E2, allowing for reliable and efficient recovery of oxygen. This configuration is particularly suitable for recovering relatively expensive oxygen.

[0046] Figure 1 In this configuration, the delivery pipeline 20 includes two parallel vaporization regulating pipe sections 23 and 24 between the return position P1 and the steam vaporizer 5. The pipeline regulating device 30 includes two vaporization regulating valves 33 and 34 disposed on the two vaporization regulating pipe sections 23 and 24. The parallel connection of the two vaporization regulating pipe sections 23 and 24 means that they share a common inlet P3 and a common outlet P4.

[0047] The backup gas supply equipment 10 may include a steam pipeline 6 for conveying hot steam s6. The steam pipeline 6 may include two parallel steam regulating pipe sections 61 and 62. The pipeline regulating device 3 also includes two steam regulating valves 361 and 362 disposed on the two steam regulating pipe sections 61 and 62. See also... Figure 1 The steam pipeline 6 includes an inlet side N6 that supplies hot steam s6 to the steam vaporizer 5 and an outlet side U6 that outputs hot steam s6 that has contributed heat from the steam vaporizer 5. Steam regulating pipe sections 61 and 62 are provided on the inlet side N6 of the steam pipeline 6.

[0048] In this way, by using a low-cost configuration, it is possible to reliably adjust and operate even when faced with huge changes in traffic during mode switching.

[0049] Preferably, the specifications of the two vaporization regulating valves 33 and 34 can be different. The specifications of the two steam regulating valves 361 and 362 can also be different. Furthermore, the flow coefficients of the two vaporization regulating valves 33 and 34 can differ by more than 20 times, and the flow coefficients of the two steam regulating valves 361 and 362 can also differ by more than 20 times. Further, the two sets mentioned above can differ by more than 50 times, for example, by about 100 times. The flow coefficient, also commonly referred to as the CV value, is an important parameter indicating the valve's flow capacity. The above arrangement is particularly suitable for both modes. Correspondingly, the pipe diameters of the two vaporization regulating pipe sections 23 and 24 can be adaptively different, and the pipe diameters of the two steam regulating pipe sections 61 and 62 can also be adaptively different.

[0050] See Figure 1 The switching assembly 3 may also include a detector 8. The detector 8 is configured to detect the gas supply status of the air separation unit 80 and issue a detection signal Sn1. The switching assembly 3 may also include a controller 7. The controller 7 is configured to issue a switching signal Sn2 based on the detection signal Sn1 from the detector 8. The switching signal Sn2 includes a control signal that selectively switches the aforementioned two vaporization regulating valves 33 and 34, selectively switches the aforementioned two steam regulating valves 361 and 362, selectively switches the aforementioned two switching valves 37 and 38, switches the reflux regulating valve 36, and regulates the operating power w4 of the backup pump 4. That is, the control signal issued by the controller 7 can control the backup pump 4 (regulating its operating power; it can be understood that adjusting the speed is also included in the power regulation), and can also control the various valves of the pipeline regulating device 30, thus controlling the vaporization flow rate f5, the steam flow rate f6, and the operating power w4, thereby achieving the switching between the two modes M1 and M2. This arrangement is particularly beneficial for automated mode switching. It can be understood that "selective switching" means that one of the two valves is opened while the other is closed. The specific switching methods for different operating conditions will be described in more detail later.

[0051] Detector 8 can be, for example, a flow detector installed in the gas supply line 87. When the flow rate here is lower than a predetermined flow rate value, controller 7 determines that the gas supply is insufficient and needs to switch to backup gas supply mode. When the flow rate here is above a certain flow rate value, controller 7 determines that the gas supply is sufficient and needs to switch back to the original normal gas supply mode. Controller 7 can be one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. Detector 8 can be, for example, various sensors, such as pressure sensors, optical sensors, ultrasonic sensors, etc.

[0052] This invention provides an air separation gas supply method M0. The air separation gas supply method M0 uses an air separation unit 80 for gas supply. Under normal operating conditions with sufficient gas supply from the air separation unit 80, gaseous product g0 is supplied to the user terminal 70 through the air separation unit 80. Simultaneously, a backup pump 4 draws pumped liquid q0 from the storage tank 1 at a low load. Most of the pumped liquid q0 is returned to the storage tank 1 as return liquid q6 through the return pipeline 26, instead of being sent to the steam vaporizer 5 (in other words, most of the pumped liquid q0 is drawn out and returned to the storage tank 1 before reaching the steam vaporizer 5, and is no longer sent to the steam vaporizer 5). A small portion of the pumped liquid q0 is sent to the steam vaporizer 5 as a vaporization stream s5 for vaporization, and then sent to the air separation unit 80 for recovery.

[0053] In the abnormal operating condition of insufficient gas supply in the air separation unit 80, the backup pump 4 is increased from a lower load to a higher load, pumping liquid q0 from the storage tank 1, and increasing the steam flow rate of hot steam s6 passing through the steam vaporizer 5. After the pumping liquid q0 is completely vaporized by the steam vaporizer 5, it is supplied to the user end 70 as gas product g0.

[0054] It can be understood that "sufficient gas supply" can be considered, for example, that the gas flow rate supplied by the air separation unit 80 can meet the gas product g0 required by the user terminal 70, for example, not less than the predetermined flow rate value. "Insufficient gas supply" can be considered, for example, that the gas flow rate supplied by the air separation unit 80 is insufficient to meet the gas product g0 required by the user terminal 70, for example, less than the predetermined flow rate value. Naturally, this also includes situations where the flow rate drops to zero, such as when the air separation unit 80 trips due to an abnormality. It can also be understood that "higher load" and "lower load" are higher and lower relative to each other.

[0055] In summary, under abnormal operating conditions, the vaporization flow rate f5 of the vaporization stream s5 is equal to the total liquid volume f0 of the pumped liquid q0, with virtually no return flow rate f1 returning to storage tank 1. Under normal operating conditions, however, the vaporization flow rate f5 accounts for only a small portion of the total liquid volume f0, while the return flow rate f1 accounts for the majority of the total liquid volume f0. The return flow rate f1 is also the flow rate of the returning liquid q6.

[0056] The aforementioned air separation gas supply method M0 allows the backup pump 4 to operate at low load even under normal operating conditions, enabling it to quickly start up to the design load to provide backup gas supply under abnormal conditions. Furthermore, under normal operating conditions, most of the pumped liquid q0 extracted by the backup pump 4 under low load operation flows back to the storage tank 1, with only a small portion being vaporized by the steam vaporizer 5 and recovered to the air separation unit 80. This not only recovers all target elements, especially oxygen during oxygen supply, but also has virtually no substantial impact on the normal operation of the air separation unit 80.

[0057] Moreover, by using a steam vaporizer 5, the steam vaporizer 5 can also be in a ready-to-operate state under normal operating conditions, which can further shorten the start-up time compared to only the backup pump 4 being in a ready-to-operate state.

[0058] Under normal operating conditions, the vaporized stream s5 accounts for less than 1 / 10 of the total liquid volume f0 of the pumped liquid q0 extracted by the backup pump 4, for example, about 1 / 20. The aforementioned lower load is the coasting load of the backup pump 4, while the aforementioned higher load is the design load of the backup pump 4. That is, under normal operating conditions, the backup pump 4 coasts, while under abnormal operating conditions, the backup pump 4 operates at its design load. It can be understood that the design load is the operating load of the pump designed for a specific pump, for example, it can be 80% to 100% of the pump's full load. The above settings can further ensure that the normal operation of the air separation unit 80 is not disturbed and are beneficial to the maintenance and operation of the backup pump 4.

[0059] like Figure 1 As shown, in the conveying pipeline 20 that pumps liquid q0 (in the corresponding normal operating mode) drawn from storage tank 1 to steam vaporizer 5, two parallel vaporization regulating pipe sections 23 and 24 are set between the return position P1 connected to the return pipeline 26 and the steam vaporizer 5, and vaporization regulating valves 33 and 34 are respectively set on the two vaporization regulating pipe sections 23 and 24.

[0060] By selectively switching the two vaporization regulating valves 33 and 34, under normal operating conditions, a small portion of the pumped liquid q0 (i.e., the vaporization stream s5) is sent to the steam vaporizer 5 for vaporization through the vaporization regulating pipe section 23, 24 with the smaller designed flow rate, such as 23. Under abnormal operating conditions, the entire pumped liquid q0 is sent to the steam vaporizer 5 for vaporization through the other vaporization regulating pipe section 24 with the larger designed flow rate. It can be understood that "smaller" and "larger" here are relative to each other. As described above, taking vaporization regulating pipe section 23 as an example, the designed flow rate of vaporization regulating pipe section 23 can be mainly determined or limited by the flow coefficient of the vaporization regulating valve 33 installed therein, and correspondingly, the pipe diameter of vaporization regulating pipe section 23 will also be adapted accordingly. In other words, a relatively large design flow rate means that the flow coefficients of the regulating valves (such as vaporization regulating valves 33 and 34 here, and steam regulating valves 361 and 362 described later) are relatively large, and correspondingly, the pipe diameter of the pipe section connecting the valve body is usually also larger. The reverse is also true.

[0061] This allows for flexible and non-destructive adjustment of the vaporization flow rate f5, which varies significantly between the two modes, and it is simple in construction and low in cost. Whether for original design or improvement upon existing facilities, it is very simple, convenient, and easy to implement.

[0062] On the steam pipeline 6 that transports hot steam s6, two parallel steam regulating pipe sections 61 and 62 are provided, and steam regulating valves 361 and 362 are respectively provided on the two steam regulating pipe sections 61 and 62.

[0063] When selectively switching the aforementioned two vaporization regulating valves 33 and 34, the two steam regulating valves 361 and 362 are also selectively switched, so that the steam flow rate f6 is lower under normal operating conditions than under abnormal operating conditions.

[0064] It is understood that, corresponding to the selective switching vaporization regulating valves 33 and 34, when opening a vaporization regulating valve with a smaller flow coefficient, such as 33, in addition to closing the vaporization regulating valve 34, the return regulating valve 36 and the recovery switching valve 38 are also opened. Furthermore, one of the two steam regulating valves 361 and 362 with a relatively smaller flow coefficient, such as 361, is also opened, and the backup switching valve 37 and the other steam regulating valve 362 with a relatively larger flow coefficient are closed. Conversely, when opening a vaporization regulating valve with a larger flow coefficient, such as 34, in addition to closing the vaporization regulating valve 33, the return regulating valve 36 and the recovery switching valve 38 are also closed, and the steam regulating valve 361 with a relatively smaller flow coefficient is closed. In addition, the backup switching valve 37 and the other steam regulating valve 362 with a relatively larger flow coefficient are opened.

[0065] In the aforementioned air separation gas supply method M0, two vaporization regulating valves 33 and 34 with flow coefficients differing by more than 20 times can be used. Alternatively, two steam regulating valves 361 and 362 with flow coefficients differing by more than 20 times can be used. That is, both the vaporization flow rate f5 and the steam flow rate f6 can reach more than 20 times, and even more than 50 times, for example, about 100 times, under abnormal operating conditions compared to normal operating conditions. In other words, the vaporization flow rate f5 under normal operating conditions is less than 1 / 20 of that under abnormal operating conditions, and therefore will not have a substantial impact on the normal operation of the air separation unit 80.

[0066] The aforementioned backup gas supply equipment 10 and air separation gas supply method M0 can achieve rapid start-up of backup gas supply and save product elements such as oxygen molecules.

[0067] Taking oxygen molecule recovery as an example, in the normal gas supply mode with the backup pump 4 coasting, both the switching valve 37 and the vaporization regulating valve 33 are closed. The reflux regulating valve 36 is open to recover gaseous oxygen, also known as GOX. At the same time, both the vaporization regulating valve 34 and the switching valve 38 are open. Some of the LOX will be vaporized in the steam vaporizer 5 through the vaporization regulating valve 34, and after becoming GOX, it will be sent back to the air separation unit 80 through the recovery pipe section 28, instead of being directly emitted.

[0068] When the text mentions liquids and gases, it usually means that 90%, 95%, or 99% or more of the components are in liquid or gaseous states, not necessarily 100% of the corresponding phase. Similarly, mentioning liquid oxygen or gaseous oxygen only requires that the content of the corresponding element, such as oxygen, is 90%, 95%, or 99% or more by volume.

[0069] Table 1 below provides examples of parameters for exemplary air separation equipment and its supporting backup gas supply equipment under two modes, corresponding to normal and abnormal operating conditions, respectively.

[0070] Table 1: Examples of parameters for exemplary air separation equipment and its supporting backup gas supply equipment under two modes corresponding to normal and abnormal operating conditions.

[0071]

[0072] Studies have shown that when the backup pump and the steam-type backup vaporizer are together in a low-load operation preparation state under normal operating conditions, the rapid start-up time is only 30 seconds. However, when only the backup pump is in a low-load operation preparation state under normal operating conditions, the start-up time is approximately 60 seconds.

[0073] It should be understood that the term "and / or" as used herein includes any and all combinations of one or more of the related listed items. Unless otherwise stated, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood in the art to which this invention pertains. It should also be understood that terms, such as those defined in common dictionaries, should be understood to have the same meaning as they have in the context of this specification and the related art, and should not be interpreted in an idealized or overly formal sense unless expressly stated herein. For the sake of brevity and / or clarity, well-known functions or constructions may not be described in detail.

[0074] Unless otherwise clearly indicated, each aspect or embodiment defined herein may be combined with any other aspect or embodiment. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

[0075] The embodiments described in this specification are merely preferred embodiments of the present invention, and are used only to illustrate the technical solutions of the present invention and not to limit the present invention. Any technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation should be within the scope of the present invention.

Claims

1. A backup gas supply device for assisting air separation equipment in gas supply, comprising a storage tank, a delivery pipeline system, and a switching assembly, wherein the delivery pipeline system includes a delivery pipeline for delivering fluid downstream from the storage tank, a backup pump is disposed on the delivery pipeline, and the delivery pipeline system further includes a return pipeline, wherein the return pipeline is configured to return a portion of the pumped liquid passed by the backup pump to the storage tank from a return position downstream of the backup pump on the delivery pipeline, characterized in that... The steam vaporizer is located downstream of the reflux position on the delivery pipeline. Downstream of the steam vaporizer, the delivery pipeline has a gas supply section and a recovery section that lead to the user end and the air separation unit, respectively. The gas supply section and the recovery section have the same inlet. The backup gas supply equipment is configured to switch between two modes via the switching component, and the switching component is configured such that, in the two modes, the operating power of the backup pump, the vaporization flow rate of the vaporized stream passing through the steam vaporizer via the backup pump, and the steam flow rate of the hot steam leading to the steam vaporizer are all different.

2. The backup gas supply equipment as described in claim 1, characterized in that, The storage tank is used to store liquid oxygen; The air separation unit includes a low-pressure tower and a high-pressure tower with relatively low and high operating pressures, a main evaporator that connects the low-pressure tower and the high-pressure tower in a heat transfer relationship, and a main heat exchanger that cools the feed air before sending it into the high-pressure tower. The outlet of the recovery pipe section is located at the main evaporator, and the recovery pipe section passes through the main heat exchanger before reaching the main evaporator.

3. The backup gas supply equipment as described in claim 1, characterized in that, The switching component includes a pipeline regulating device configured to adjust the vaporization flow rate and the steam flow rate.

4. The backup gas supply equipment as described in claim 3, characterized in that, The pipeline regulating device includes two switching valves respectively disposed in the gas supply pipeline section and the gas recovery pipeline section; The pipeline regulating device includes a reflux regulating valve disposed in the reflux pipeline.

5. The backup gas supply equipment as described in claim 4, characterized in that, The air separation unit also has gas delivery pipelines and liquid delivery pipelines that supply gas to the user end and output liquid products to the storage tank, respectively. The outlet of the gas transmission pipeline is located downstream of the corresponding switching valve of the gas supply pipeline section.

6. The backup gas supply equipment as described in claim 3, characterized in that, The delivery pipeline includes two parallel vaporization regulating pipe sections between the reflux position and the steam vaporizer, and the pipeline regulating device includes two vaporization regulating valves disposed in the two vaporization regulating pipe sections; The backup gas supply equipment includes a steam pipeline for conveying the hot steam, the steam pipeline includes two steam regulating pipe sections connected in parallel, and the pipeline regulating device further includes two steam regulating valves disposed in the two steam regulating pipe sections.

7. The backup gas supply equipment as described in claim 6, characterized in that, The two vaporization regulating valves are of different specifications; The two steam regulating valves are of different specifications.

8. The backup gas supply equipment as described in claim 7, characterized in that, The flow coefficients of the two vaporization regulating valves differ by more than 20 times; The flow coefficients of the two steam regulating valves differ by more than 20 times.

9. The backup gas supply equipment as described in claim 6, characterized in that, The switching component also includes: The detector is configured to detect the gas supply status of the air separation unit and issue a detection signal; and / or The controller is configured to issue a switching signal based on the detection signal from the detector. The switching signal includes a control signal that selectively switches the two vaporization regulating valves, selectively switches the two steam regulating valves, selectively switches the two switching valves, switches the reflux regulating valve, and adjusts the operating power of the backup pump.

10. An air separation gas supply method, comprising supplying gas using air separation equipment, characterized in that, Under normal operating conditions with sufficient gas supply, the air separation unit supplies gas products to the user end. At the same time, the backup pump draws pumped liquid from the storage tank at a low load. Most of the pumped liquid is returned to the storage tank as return liquid through the return pipeline instead of being sent to the steam vaporizer. A small portion of the pumped liquid is sent to the steam vaporizer as a vaporization stream for vaporization and then sent to the air separation unit for recovery. In the abnormal operating condition of insufficient gas supply to the air separation unit, the backup pump is increased from the lower load to the higher load, pumping liquid from the storage tank and increasing the steam flow rate of the hot steam passing through the steam vaporizer. After the pumped liquid is completely vaporized by the steam vaporizer, it is supplied to the user as a gaseous product.

11. The air separation gas supply method as described in claim 10, characterized in that, Under normal operating conditions, the vaporized stream accounts for less than 1 / 10 of the total amount of pumped liquid extracted by the backup pump. The lower load is the coasting load of the backup pump, and the higher load is the design load of the backup pump.

12. The air separation gas supply method as described in claim 10 or 11, characterized in that, On the pipeline that pumps the liquid drawn from the storage tank to the steam vaporizer, two vaporization regulating pipe sections are set in parallel between the return position connected to the return pipeline and the steam vaporizer, and vaporization regulating valves are respectively installed on the two vaporization regulating pipe sections. By selectively switching the two vaporization regulating valves, under normal operating conditions, a small portion of the pumped liquid is sent to the steam vaporizer for vaporization through the vaporization regulating pipe section with a relatively smaller designed flow rate, while under abnormal operating conditions, the entire pumped liquid is sent to the steam vaporizer for vaporization through the other vaporization regulating pipe section with a relatively larger designed flow rate.

13. The air separation gas supply method as described in claim 12, characterized in that, Two parallel steam regulating pipe sections are provided on the steam pipeline that transports the hot steam, and steam regulating valves are respectively installed on the two steam regulating pipe sections. When selectively switching the two vaporization regulating valves, the two steam regulating valves are also selectively switched, such that the steam flow rate under normal operating conditions is lower than that under abnormal operating conditions.

14. The air separation gas supply method as described in claim 13, characterized in that, The two vaporization regulating valves with flow coefficients differing by more than 20 times are used; The two steam regulating valves with flow coefficients differing by more than 20 times are used.

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