CN117803858A - Air supply system, air supply method and air separation system - Google Patents

Abstract

The invention provides a gas supply system, a gas supply method and an air separation system. In the air supply system, a first air supply pipeline and a second air supply pipeline of an air supply pipe network are used for respectively supplying pressurized air which is pressurized to a first pressure and a second pressure by a first compressor and a second compressor to two air utilization ends, wherein the first pressure and the second pressure are different. One end of the first standby pipeline is connected with the outlet of the standby compressor, and the other end of the first standby pipeline is connected with the first air supply pipeline. The two ends of the temporary connecting pipeline are respectively connected into the first air supply pipeline and the second air supply pipeline. The pipeline element is arranged in the air supply pipe network and is arranged to switch the on-off state of the first standby pipeline and the temporary connection pipeline. The gas supply system can ensure continuous gas supply for the required gas.

Description

Air supply system, air supply method and air separation system

Technical Field

The invention belongs to the field of air supply, relates to an air supply system and an air supply method, and particularly relates to an air separation system.

Background

In air separation plants, the feed air is often compressed to a predetermined pressure by means of a compressor, and after purification by purification means, the air separation rectification column is supplied with pressurized feed air. The user of the air separation plant often also requires a demand gas, also referred to herein as instrument gas, at a predetermined pressure to supply to other external devices other than the air separation plant, which may be collectively referred to herein as factory floor instruments.

The required pressure of the instrument gas is often different compared to the feed air. Moreover, sometimes, the supply requirements of the user for the instrument gas are very strict, and strict guarantee is necessary for the non-interruption. However, the corresponding compressor for pressurization often fails, and this supply is interrupted at this time.

Therefore, how to meet the strict requirements of such demand gases in terms of continuous gas supply is a problem to be solved.

Disclosure of Invention

The invention aims to provide a gas supply system which can ensure continuous gas supply for required gas.

The invention provides an air supply system. The air supply system comprises an air supply pipe network, a first compressor and a second compressor. The air supply pipe network comprises a first air supply pipeline and a second air supply pipeline, and the air supply pipeline is used for supplying pressurized air pressurized to a first pressure and a second pressure by the first compressor and the second compressor to two air utilization ends respectively, wherein the first pressure and the second pressure are different. The air supply system further comprises a standby compressor and pipeline elements, and the air supply pipe network further comprises a first standby pipeline and a temporary connecting pipeline. One end of the first standby pipeline is connected with the outlet of the standby compressor, and the other end of the first standby pipeline is connected with the first air supply pipeline. The two ends of the temporary connecting pipeline are respectively connected into the first air supply pipeline and the second air supply pipeline. The pipeline element is arranged in the air supply pipe network and is arranged to switch the on-off state of the first standby pipeline and the temporary connection pipeline.

In one embodiment, the air supply system further comprises a first purifying device and a second purifying device respectively arranged on the first air supply pipeline and the second air supply pipeline for purifying the pressurized air pressurized by the first compressor and the second compressor respectively. The temporary connection line and the first backup line are connected downstream and upstream of the first purification device, respectively.

In one embodiment, the air supply network further comprises a second standby pipeline, one end of the second standby pipeline is connected with the outlet of the standby compressor, and the other end of the second standby pipeline is connected with the second air supply pipeline. The temporary connection line and the second backup line are connected downstream and upstream of the second purification device, respectively.

In one embodiment, the air supply system further comprises a controller arranged to send a switching signal to switch the line element to the on-off state of the temporary connection line and the backup line and to vary the load of the backup compressor and optionally also the load of the second compressor. The air supply system further includes a detector for detecting a state of each compressor and transmitting a detection signal to the controller, and the controller transmits a switching signal according to the detection signal.

In one embodiment, the gas supply system further comprises a gas buffer tank, the gas buffer tank being connected to the first gas supply line.

In one embodiment, each compressor is configured identically.

The invention also provides a gas supply method. The air supply method adopts the air supply system. The air supply method comprises the following steps: in a normal operation state, raw material air is pressurized to a first pressure by a first compressor of the air supply system and then supplied to a first air end, and raw material air is pressurized to a second pressure by a second compressor of the air supply system and then supplied to a second air end; in a first fault state of the first compressor fault, pressurizing raw material air through the second compressor and then supplying the pressurized raw material air to the first gas end, and starting the standby compressor in a first period; then, when the standby compressor reaches a predetermined load, the raw material air is pressurized to a first pressure by the standby compressor in a second period subsequent to the first period, and then supplied to the first gas side.

In one embodiment, in a second failure state in which the second compressor fails, the raw material air is pressurized by the backup compressor and then sent to the second air-using end.

In one embodiment, the first pressure and the second pressure are within 30% of each other. The air flow rates required for the two air-using ends are within 50% of each other.

In one embodiment, when the second pressure is less than the first pressure, increasing the load of the second compressor for a first period of time until the pressurized air pressurized by the second compressor changes from the second pressure to the first pressure; when the second pressure is greater than the first pressure, the load of the second compressor is maintained for a first period of time, the feed air continues to be pressurized to the second pressure, and is depressurized to the first pressure by a pressure relief valve upstream of the first gas end.

In one embodiment, during a first period, detecting a pressure of pressurized air supplied by a second compressor; when the pressure of the pressurized air is lower than the first pressure, buffer gas is supplied to the first gas end through the gas buffer tank to keep the pressurized air supplied to the first gas end at the first pressure.

In one embodiment, the compressors are made to adopt the same configuration.

In one embodiment, the higher priority gas consumer is identified as the first gas consumer by determining the priority of the two gas consumers for continuous gas supply demand.

The invention also provides an air separation system, which comprises an air separation rectifying tower and a factory instrument. The air separation system further comprises the air supply system, and the factory instrument and the air separation rectifying tower respectively form two air utilization ends connected with a first air supply pipeline and a second air supply pipeline of the air supply system.

When the air supply system and the air supply method are adopted, when the first compressor which defaults to supply air to the first air end fails and cannot supply air, the temporary connecting pipeline is immediately in a communication state, so that the second compressor which defaults to supply air to the second air end and is running at the moment is utilized to supply air to the first air end, and the standby compressor is started at the same time. The first gas end has higher requirement for continuous gas supply than the second gas end, in other words, has higher priority. And then, when the standby compressor is completely started and reaches the corresponding load, the first standby pipeline is connected again, and the temporary connection pipeline is closed, so that the standby compressor takes over the second compressor to supply air to the first air end. The whole supply process of the required gas for the first gas end is very smooth, so that continuous gas supply for the corresponding required gas can be ensured.

The air supply system is adopted by the air separation system, so that the air separation equipment can be fully utilized to ensure continuous supply of instrument air to instruments in a factory.

Drawings

The advantages and spirit of the present invention may be further understood by reference to the following detailed description of the invention and the accompanying drawings.

Fig. 1 is a schematic diagram showing an exemplary configuration of an air supply system.

Fig. 2 is a flow chart illustrating exemplary steps of a method of supplying air.

Fig. 3 is a flow chart illustrating how the second compressor supplies air to the first air side.

Detailed Description

Specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention should be understood not to be limited to such an embodiment described below, and the technical idea of the present invention may be implemented in combination with other known technologies or functions, or other technologies identical to those known technologies.

The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the present specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

In the description of the present invention, the meaning of "a plurality" is two or more (i.e., two or more) unless explicitly specified otherwise. Likewise, the appearances of the phrase "a" or "an" in this document are not meant to be limiting, but rather describing features that have not been apparent from the foregoing. Likewise, unless a particular quantity of a noun is to be construed as encompassing both the singular and the plural, both the singular and the plural may be included in this disclosure. Likewise, modifiers that appear before the term "about" or "approximately" in this text generally include the present number, and their specific meaning should be understood in conjunction with the context.

As mentioned before, engineering applications, in particular in the application of air separation plants, often encounter two gas requirements, for example, instrument gas and rectifying column feed air. There is a need to be able to reliably meet such gas demand that is stringent for sustained gas use.

The inventors have analyzed that a backup compressor may be provided to take over the first compressor in the event of a failure of the compressor (referred to as the first compressor) that pressurizes air to provide instrument gas.

However, the inventors contemplate that it takes a short time, typically, more than about thirty minutes, to actually start the backup compressor to a predetermined load to pressurize the air to a predetermined pressure.

In this regard, the inventors further analyzed that although it is desirable to be able to supply continuously, similar to the instrument gas, in practice the feed air and instrument gas are different in the requirement for continuous supply, i.e. in the priority for continuous supply. Typically, the meter gas is higher priority than the feed air. It is particularly mentioned that air separation plants often have a backup system on their own and can therefore be replenished by the backup system even if the air supply is interrupted for a period of time.

The inventors have therefore analyzed that such a difference in priority can be exploited to achieve a reliable and continuous supply of higher priority gas demand, such as meter gas.

Fig. 1 shows an example configuration of an air supply system 10. It is to be understood that the drawings are by way of example only and are not necessarily drawn to scale and that the scope of the invention as claimed should not be construed as being limited thereto.

The air supply system 10 comprises an air supply network 1, a first compressor 21 and a second compressor 22. The air supply network 1 comprises a first air supply line 11 and a second air supply line 12 for supplying pressurized air g1, g2 pressurized to a first pressure P1 and a second pressure P2 via a first compressor 21 and a second compressor 22 to two air utilization ends E1, E2, respectively. Wherein the first pressure P1 and the second pressure P2 are different. In other words, the two air-use ends E1, E2 have different requirements for the pressure of the required air.

It is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not intended to be limiting with respect to time sequence, number, or importance, but are not to be construed as indicating or implying a relative importance or implicitly indicating the number of features indicated, but merely for distinguishing one feature from another in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

It will also be appreciated that when describing pressure herein, natural pressure losses are generally not considered. If the pressure difference between the respective parts is not greater than the natural line loss caused by the pressure loss in the piping, heat exchanger, cooler, adsorber, ordinary regulating valve (non-throttle valve, purge valve) or the like, the pressure is still evaluated as "equal" here even if the magnitude of such natural line loss is not small. Conversely, the pressure of the flow downstream of certain process steps is described as "lower" or "higher" than the pressure upstream of these process steps only if the corresponding pressure difference is higher than the natural line loss, i.e. in particular the pressure is reduced by at least one compressor stage boost pressure or purposefully by at least one throttle valve or pressure reducing valve or the like.

The "air-using end" is any unit that needs to use pressurized air, and can be specific equipment or any facility or place. The pressure of the pressurized air is generally not less than 2bar, where bar refers to absolute pressure.

The air supply system 10 further comprises a backup compressor 23 and a piping element 4. The air supply network 1 further comprises a first backup line 15 and a temporary connection line 18.

One end (i.e., upstream end) of the first backup line 15 is connected to the outlet of the backup compressor 23, and the other end (i.e., downstream end) is connected to the first air supply line 11.

The first air supply pipeline 11 and the second air supply pipeline 12 are respectively connected to two ends of the temporary connection pipeline 18.

The line element 4 is arranged in the air supply line network 1 and is arranged to switch the on-off state of the first backup line 15 and the temporary connection line 18. In particular, the line element 4 can be various valves, such as solenoid valves, pneumatic valves, manual valves, etc. In fig. 1, the piping element 4 may include a control valve 45 and a control valve 48 provided in the first backup piping 15 and the temporary connection piping 18, respectively, and may control the on-off of the first backup piping 15 and the temporary connection piping 18 by switching itself.

It is to be understood that as used herein, "piping," "tubing," "pipe section," and the like refer to lines through which a stream flows and are not intended to limit the physical form of the corresponding elements. Taking a "pipeline" as an example, a pipeline may refer to a segment of a complete pipeline. The pipeline can also be a combination of a plurality of pipelines which are connected in sequence. The multiple lines may be connected by pipe joints or by other piping elements such as valves. The space in the pipe connection or other pipe element through which the flow passes can also be considered part of the pipe.

When the air supply system 10 is used, the second compressor 22 and/or the backup compressor 23 can be used for supplying air to the first air end E1 by switching the on-off state of the first backup pipeline 15 and the temporary connection pipeline 18 when the first compressor 21 fails, so that the air supply can be ensured to be uninterrupted. In particular, the first gas side E1 can be supplied with gas by the already running second compressor 22 in the event that the backup compressor 23 is started but not yet fully started. When the standby compressor 23 has been fully started to a predetermined load, it is switched to the standby compressor 23 to supply the first air terminal E1 with air. This can increase the reliability of the continuous supply of air to the first air terminal E1. Moreover, the air supply system 10 is simple in overall construction and low in cost.

In fig. 1, the air supply system 10 may further include a first purifying device 51 and a second purifying device 52, which may be provided in the first air supply line 11 and the second air supply line 12, respectively, for purifying the pressurized air g1, g2 pressurized by the first compressor 21 and the second compressor 22, respectively. The purification devices 51, 52 may dewater and/or decarbonize the pressurized air, for example, may provide dewatered decarbonized air (CFA).

In fig. 1, temporary connection 18 and first backup line 15 may be connected downstream and upstream, respectively, of first purification device 51. It will be understood that when "upstream" and "downstream" are used herein to describe relative orientations, the expressions are relative to the direction of flow of the flow in the corresponding conduit.

As shown in fig. 1, the air supply network 1 may also comprise a second backup line 16. One end (i.e., the upstream end) of the second backup line 16 is connected to the outlet of the backup compressor 23, and the other end (i.e., the downstream end) is connected to the second air supply line 12. In this way, the backup compressor 23 can simultaneously serve as a backup for the second compressor 22. In fig. 1, temporary connection 18 and second backup line 16 may be connected downstream and upstream, respectively, of second purification device 52. This integrated arrangement can maintain the supply of air to the second air terminal E2 by avoiding the installation of one more standby machine.

As shown in fig. 1, the air supply system 10 may further include a controller 3. The controller 3 may be arranged to send a switching signal Sh to switch the line element 4 to the on-off state of the temporary connection line 18 and the backup lines (15 and optionally 16) 15, 16 and to vary the load of the backup compressor 23 and optionally also of the second compressor 22. It will be appreciated that "optionally" as used herein means that the controller 3 may or may not vary the load of the second compressor 22. Preferably, the controller 3 may control the load variation of the second compressor 22. It will be appreciated that "varying the load" includes not only the load being regulated within an adjustable range as is commonly understood, but also, for example, switching of the load between zero and non-zero, i.e., including a switch.

The air supply system 10 may further comprise a detector 6 for detecting the status of the respective compressors 21, 22, 23 and for sending a detection signal Sc to the controller 3. The controller 3 may transmit the switching signal Sh in accordance with the detection signal Sc.

The detector 6 may be, for example, various sensors such as a pressure sensor, an optical sensor, an ultrasonic sensor, and the like. Furthermore, the detector 6 may be provided separately or integrated in a system component, for example the compressors 21, 22 etc. may be provided with a fault detector (mentioned later, inlet guide vane provided with a pressure sensor) and send a trip signal as a detection signal Sc to the controller 3. The controller 3 may 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 a combination thereof.

In fig. 1, the gas supply system 10 may further include a gas buffer tank 7. The gas buffer tank 7 can be connected to a first gas supply line 11. In fig. 1, the access position of the temporary connection line 18 may be closer to the first compressor 21 than the access position of the gas buffer tank 7. That is, in the first air supply line 11, the access position of the temporary connection line 18 is located at a position further downstream. The provision of the gas buffer tank 7 makes it possible to compensate for pressure gaps, ensuring pressure stability, especially during switching. In practice, the gas buffer tank 7 may be set according to the pressure fluctuation demand of the first gas supply line 11.

As shown in fig. 1, the compressors 21, 22, 23 may all be configured identically. That is, the compressors 21, 22, 23 may be selected to be the same model. Therefore, the standby can be conveniently switched, and convenience can be provided in various stages of design, purchase, operation and the like.

In the air supply system 10 of fig. 1, control valves 41, 42, 43, which may be referred to as outlet valves, are also shown, which are provided at the outlets of the compressors 21, 22, 23, respectively. By closing such an outlet valve, it is better ensured that no further downstream air supply via the compressors 21, 22, 23 is possible. It is described herein that when a compressor fails and thus is shut down, it can be ensured that ambient air does not pass the corresponding compressor and be fed downstream by closing the corresponding such outlet valve.

In fig. 1, a control valve 44 is also shown, arranged in the second air supply line 12 downstream of the corresponding access position of the temporary connection line 18. If switching from the normal operation state in which the second air end E2 is supplied with air by the second compressor 22 to a first failure state (to be described later) in which the first air end E1 is supplied with air by the second compressor 22, the air supply to the second air end E2 may be stopped by closing the control valve 44 while the control valve 48 is opened.

In fig. 1, control valves 47, 48 are also shown immediately upstream of the purification devices 51, 52, respectively. In the event of a failure of the corresponding purification device 51 or 52, the corresponding control valve 47 or 48 may be closed, thereby stopping further intake to the downstream purification device.

The control valves such as 41, 44, 46 shown in fig. 1 can be regarded as a part of the pipeline element 4, and can be controlled by the controller 3 to switch the pipeline on/off and the operation modes.

As mentioned before, the invention also provides a method F0 for gas supply. The air supply method F0 may employ the air supply system 10 described above. The air supply method F0 can be generally seen in fig. 2. The air supply method F0 includes, in a normal operation state (i.e., in a normal case), supplying the raw material air to the first air side E1 after pressurizing the raw material air to the first pressure P1 (i.e., becoming the pressurized air g 1) by the first compressor 21 of the air supply system 10, and supplying the raw material air to the second air side E2 after pressurizing the raw material air to the second pressure P2 (i.e., becoming the pressurized air g 2) by the second compressor 22 of the air supply system 10, as by step S1.

In a first failure state in which the first compressor 21 fails (i.e., if the first compressor 21 fails), the raw material air is pressurized by the second compressor 22 and supplied to the first air side E1 in the first period T1, and the backup compressor 23 is turned on as by step S31. That is, it may be determined in, for example, step S21 whether the first compressor 21 is malfunctioning, for example, by the detector 6 detecting whether the first compressor 21 is malfunctioning, thereby providing the corresponding detection signal Sc. If so, for example, the controller 3 sends a switching signal Sh to cause the corresponding component to perform the following step S21; if not, returning to the normal running state. Similar decisions as described below may be implemented by the hardware described above.

Then, after the backup compressor 23 reaches a predetermined load (for example, the load corresponds to 70% to 105%, such as 100%, of the full load), the raw material air is supplied to the first air side E1 after being pressurized to the first pressure P1 (i.e., changed to the pressurized air g 3) by the backup compressor 23 in the second period T2 subsequent to the first period T1, in place of the second compressor 22, as by step S51. That is, it may be determined whether the backup compressor 23 is ready at, for example, step S41. For example, whether the pressurized air g3 supplied from the backup compressor 23 reaches the first pressure P1 may be detected by a detecting element 65 (e.g., a pressure sensor) located downstream of the control valve 45 in the first backup line 15 in fig. 1, thereby determining whether the backup compressor 23 reaches the corresponding predetermined load. Similarly, a sensing element 66 downstream of the control valve 46 is also shown in FIG. 1. If yes, execute the following step S51; if not, returning to the original running state.

It will be appreciated that, after the backup compressor 23 takes over the supply of the pressurized air g3 from the second compressor 22 to the first air side E1, the second compressor 22 may continue to return to the normal state of supplying the pressurized air g2 at the second pressure P2 to the second air side E2.

When the above-mentioned air supply method F0 is adopted, the first compressor 21 is temporarily replaced with the second compressor 22 which is currently supplying air and is under a larger load to supply air to the first air end E1 when the first compressor 21 fails, and the standby compressor 23 is turned on at the same time. After the standby compressor 23 reaches the required load, the standby compressor 23 is used to supply air to the first air end E1. The second compressor 22 can return to its original role again and continue to supply air to the second air utilization end E2.

The air supply method F0 can realize continuous air supply of the first air end E1, and is high in reliability. Moreover, the original first compressor 21 is fully utilized to be matched with the standby compressor 23, so that the structure is simple and the cost is low.

With continued reference to fig. 2, in the second failure state in which the second compressor 22 fails (i.e., if the second compressor 22 fails), the raw material air is pressurized by the backup compressor 23 (i.e., becomes pressurized air g 3) and then sent to the second air end E2 as by step S32. For example, the pressure of the pressurized air g3 supplied from the backup compressor 23 may be made to reach the desired pressure (second pressure P2) of the second air use end E2 by making the backup compressor 23 reach a predetermined load corresponding to the second pressure P2. In other words, the load of the backup compressor 23 can be adjusted, and at least the load corresponding to the first pressure P1 and the load corresponding to the second pressure P2 can be switched. For example, the load of the compressor 23 and the later-mentioned compressor 22 may be adjusted by adjusting the posture of the own Inlet Guide Vanes (IGVs). As shown in fig. 2, it is determined in step S22 whether the second compressor 22 is malfunctioning. If yes, execute the following step S32; if not, returning to the normal running state. In fig. 2, if the first compressor 21 fails and if the second compressor 22 fails are two steps that are completely independent, for example, if the first compressor 21 or the second compressor 22 feeds back a skip signal to the controller 3 to determine whether each fails, and if there is no feedback signal, the corresponding determination result is no by default. There is typically very little simultaneous failure of the first compressor 21 and the second compressor 22. For example, if both fail at the same time, an early warning signal may be provided, for example, informing the operator to handle.

The above-described air supply method F0 may further share the spare compressor 23 while being a spare for the second compressor 22. Further compressing the cost.

As described above, the compressors 21, 22, 23 can be configured in the same manner. Thus, the switching is convenient to adjust.

In particular, the first pressure P1 and the second pressure P2 may differ from each other by within 30%. The air flow rates required for the two air-using ends E1, E2 may differ from each other by within 50%, further within 30%, still further within 10%. Here, "mutually different" may be based on the one with the larger value in both. That is, of the air flow rates (which may be in a standard cube) required for the two air ends E1, E2, if the air flow rate required for the air end E1 is large, 50% of the air flow rate required for the air end E1 is used as the upper limit of the difference between the two. This facilitates the adjustment of the switching, especially in case the same configuration is used in connection with each compressor 21, 22, 23.

Fig. 3 shows an exemplary description of how the second compressor 22 supplies air to the first air side E1. As shown in fig. 3, when the second pressure P2 is smaller than the first pressure P1, the load of the second compressor 22 is increased for the first period T1 until the pressurized air g2 pressurized by the second compressor 22 is changed from the second pressure P2 to the first pressure P1, as shown in step S3021. That is, it may be determined, for example, in step S301, whether the pressure (second pressure P2) at which the second compressor 22 is currently pressurizing is smaller than the required pressure (first pressure P1) of the first gas end E1, and if so, step S3021 is performed.

With continued reference to fig. 3, when the second pressure P2 is greater than the first pressure P1, during the first period T1, the load of the second compressor 22 is maintained, the raw material air is continuously pressurized to the second pressure P2, and is depressurized to the first pressure P1 by a depressurization valve (i.e., the control valve 48 in fig. 1) upstream of the first gas end E1, as shown in step S3022. Since the first pressure P1 and the second pressure P2 are different, when the determination result is no in step S301 in fig. 3, step S3022 may be executed.

In the embodiment shown in fig. 1, the pressure of the pressurized air g2 supplied by the second compressor 22 may be detected during the first period T1. When the pressure of the pressurized air g2 is lower than the first pressure P1, the buffer air g7 may be supplied to the first air end E1 through the air buffer tank 7 to maintain the pressurized air supplied to the first air end E1 at the first pressure P1. In this way, the air pressure stability of the first air end E1 can be ensured.

As shown in fig. 2, in the air supply method F0, by determining the priority of two air-using ends for the continuous air supply demand, the air-using end with higher priority is determined as the first air-using end 1, as by step S0. Step S0 may be performed before step S21 is performed, illustrated in fig. 2 even before step S1.

It will be appreciated that the higher priority air-consuming end is defined as the first air-consuming end E1, i.e. the set of air-supplying components, such as compressors, air-supplying lines, purifying devices, etc., to which air is originally supplied are defined as the first compressor 21, the first air-supplying line 11, the first purifying device 51, etc., as described above.

The air supply method F0 may also be referred to as an air supply control method. It is to be understood that the method steps described herein are not necessarily performed in the order described, but may be varied in a logical manner, unless otherwise indicated. For example, the determination step S301 may be performed even before or at the very beginning of the whole air supply method F0, so that if the step S31 is performed and the first air end E1 needs to be supplied with air by using the second compressor 22 instead of the failed first compressor 21 temporarily, it may be determined whether to perform the step S3021 or the step S3022 directly.

In the embodiment shown in fig. 1, two air supply lines 11, 12 are each provided with a purification device 51, 52. If the first purifying device 51 fails, the temporary connection line 18 may be connected, and the first air end E1 may be temporarily supplied with air by the second compressor 22 and the second purifying device 52, just as in the aforementioned first period T1. The first purification device 51 is restored (e.g., replaced with new adsorbent material and is ready) and returned to normal operation. If the second purifying device 52 fails, a standby system of the air separation rectifying tower can be started, and the second purifying device 52 is recovered and then returns to the normal running state.

Fig. 1 essentially illustrates a space division system 100. The air separation system 100 includes an air separation rectifying column and factory floor instrumentation, and also includes the air supply system 10 described above. The factory instruments and the air separation rectifying tower respectively form two air utilization ends E1 and E2 which are connected with a first air supply pipeline 11 and a second air supply pipeline 12 of the air supply system 10.

The air separation rectifying tower forming the air end E2, namely the tower body for separating air by rectification in air separation equipment to produce various air products, is usually positioned in a cold box. It will be appreciated that where a stream is described herein as entering a first element and a second element in sequence, or where similar descriptions are used, that is merely indicative of the sequence in which the stream enters the first element and the second element, it is not excluded that the stream also passes through a third element between the first element and the second element, nor that the stream also passes through the third element before the first element or after the second element. Here, the pressurized air g2 is typically also passed through a main heat exchanger, but also through other elements such as an expander, downstream of the purification device 52 before being fed to the air separation rectifying column.

Factory floor instruments are a generic term for other external air utilization devices or sites other than air separation plants, such as welding equipment, that are typically located on the same factory floor.

An exemplary air supply system that may be constructed in practice and a corresponding air supply control process are described below by way of example with respect to the air separation system 100.

The air pressure required for the plant instrumentation and the air separation rectification column was about 5.5bara and 4.5bara, respectively. As mentioned previously, the instrument gas is more stringent than the air separation plant for continuous gas supply.

The three compressors 21, 22, 23 are designed and selected to be of the same model, with the same design flow and pressure. The three compressors 21, 22, 23 may each be provided with an outlet pressure control element on the respective inlet guide vane, so that they may be operated at different outlet pressures and flows.

The control valves 45, 46 and 48, etc. may be automatic valves, which are kept closed at ordinary times (i.e. in normal operation) in order to isolate the two air supply lines 11, 12. In terms of pressure control and flow control, the two air supply lines 11, 12 can be operated independently.

If the first compressor 21 fails, the purification device 51 is stopped; stopping the air separation rectifying tower and automatically starting a standby system associated with the air separation rectifying tower; the control valve 48 is opened and then the load of the second compressor 22 is increased such that the outlet pressure of the second compressor 22 is from the second pressure P2 to the first pressure P1, the second compressor 22 and the purifying means 52 being used to supply the instrument gas. At the same time, the backup compressor 23 is turned on. When the backup compressor 23 is ready to deliver air at the first pressure P1 to the purification apparatus 51, the control valve 45 is opened, the control valve 48 is closed, and the purification apparatus 51 is restarted. The instrument gas can now be supplied via the backup compressor 23 and the purification device 51. The second compressor 22 and the purification device 52 may be isolated to supply air to the air separation rectification column. Finally, in practice, the air separation rectifying column may be restarted, and the first compressor 21 restarted to switch back.

If the second compressor 22 fails, the air separation column is stopped. At this time, the standby system of the air separation rectifying tower can be automatically started. The backup compressor 23 is started on time and then the air separation rectifying column is restarted.

The above-described air supply control allows for a short time (about 30 minutes or more depending on the model) required for the standby compressor 23 to start up, and the second compressor 22 can be operated to increase the outlet pressure from the second pressure P2 to the first pressure P1 in a shorter time (about 2-3 minutes). The second compressor 22 is thus first used as a first backup for the first compressor 21, increasing the load. At this point, the air separation rectifying column may be stopped for a short period of time (about 30 minutes or more, depending on the type of machine). During this time, the backup system of the air separation rectifying tower can also be automatically started.

Each aspect or embodiment defined herein may be combined with any other aspect or embodiment unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

The preferred embodiments of the present invention are described in this specification, which are intended to be illustrative of the technical solution of the present invention and not limiting. All technical solutions that can be obtained by logic analysis, reasoning or limited experiments according to the inventive concept by those skilled in the art shall be within the scope of the present invention.

Claims (14)

1. An air supply system comprising an air supply network, a first compressor and a second compressor, said air supply network comprising a first air supply line and a second air supply line for supplying pressurized air pressurized to a first pressure and a second pressure via said first compressor and said second compressor, respectively, to two air utilization terminals, wherein said first pressure and said second pressure are different,

the air supply system also comprises a standby compressor and a pipeline element, and the air supply pipe network also comprises a first standby pipeline and a temporary connecting pipeline;

one end of the first standby pipeline is connected with the outlet of the standby compressor, and the other end of the first standby pipeline is connected with the first air supply pipeline;

two ends of the temporary connecting pipeline are respectively connected into the first air supply pipeline and the second air supply pipeline;

the pipeline element is arranged in the air supply pipe network and is arranged to switch the on-off state of the first standby pipeline and the temporary connection pipeline.

2. The air supply system of claim 1, further comprising first and second purifying means disposed in the first and second air supply lines, respectively, for purifying pressurized air pressurized by the first and second compressors, respectively;

the temporary connection line and the first backup line are connected downstream and upstream of the first purification device, respectively.

3. The air supply system of claim 2, wherein the air supply network further comprises a second backup line, one end of the second backup line is connected to the outlet of the backup compressor, and the other end of the second backup line is connected to the second air supply line;

the temporary connection line and the second backup line are connected downstream and upstream of the second purification device, respectively.

4. The gas supply system according to claim 1 to 3,

the gas supply system further comprises a controller arranged to send a switching signal to cause the line element to switch the on-off state of the temporary on-line and the backup line and to cause the backup compressor to vary load, optionally also the second compressor;

the air supply system further includes a detector for detecting a state of each compressor and transmitting a detection signal to the controller, the controller transmitting the switching signal according to the detection signal.

5. A gas supply system according to any one of claims 1 to 3, further comprising a gas buffer tank, the gas buffer tank being connected to the first gas supply line.

6. A gas supply system as claimed in any one of claims 1 to 3, wherein each compressor is of the same configuration.

7. A gas supply method, characterized in that the gas supply system according to any one of claims 1 to 6 is employed, the gas supply method comprising:

in a normal operation state, raw material air is pressurized to a first pressure by a first compressor of the air supply system and then supplied to a first air end, and raw material air is pressurized to a second pressure by a second compressor of the air supply system and then supplied to a second air end;

in a first failure state in which the first compressor fails, pressurizing feed air by the second compressor and then supplying the pressurized feed air to the first gas side, and turning on the backup compressor for a first period of time; then, when the backup compressor reaches a predetermined load, the raw material air is pressurized to a first pressure by the backup compressor in a second period subsequent to the first period, and then supplied to the first gas end.

8. The method of supplying gas according to claim 7, wherein,

and in a second fault state of the second compressor fault, pressurizing raw material air through the standby compressor and then sending the raw material air into the second gas-using end.

9. The method of supplying gas according to claim 7, wherein,

the first pressure and the second pressure differ from each other by within 30%;

the air flow rates required for the two air-using ends are within 50% of each other.

10. The method of supplying gas according to claim 7, wherein,

increasing the load of the second compressor for the first period of time when the second pressure is less than the first pressure until the pressurized air pressurized by the second compressor changes from the second pressure to the first pressure;

when the second pressure is greater than the first pressure, during the first period, maintaining the load of the second compressor, continuing to pressurize the feed air to the second pressure, and reducing to the first pressure by a pressure reducing valve upstream of the first gas end.

11. The air supply method according to claim 7, wherein the pressure of the pressurized air supplied from the second compressor is detected during the first period;

and supplying buffer gas to the first gas end through a gas buffer tank when the pressure of the pressurized air is lower than the first pressure so as to keep the pressurized air supplied to the first gas end at the first pressure.

12. The air supply method as set forth in claim 7, wherein each compressor is made to adopt the same configuration.

13. The air supply method according to claim 7, wherein the air-using end with the higher priority is determined as the first air-using end by determining the priority of the two air-using ends for the continuous air supply demand.

14. An air separation system comprising an air separation rectifying tower and a factory floor instrument, and further comprising the air supply system of any one of claims 1 to 6, wherein the factory floor instrument and the air separation rectifying tower respectively form two air utilization ends connected with a first air supply pipeline and a second air supply pipeline of the air supply system.