Remote automatic control series air supply method for centrifugal compressor

Abstract

The invention provides a centrifugal compressor remote automatic control series air supply method which comprises the following steps: controlling an air compressor and a supercharger to enter a series preparation state through a group control assembly after receiving a series air supply instruction, and opening a medium-pressure air supply valve between the air compressor and the supercharger after the air compressor and the supercharger enter the series preparation state; an air compressor starting instruction sent by the group control assembly after the medium-pressure air supply valve is opened is received through the air compressor control assembly so as to start an air compressor, and supercharger inlet pressure is established through an air inlet valve and an exhaust emptying valve; through a supercharger control assembly, a supercharger starting instruction sent by the group control assembly is received to start a supercharger, and supercharger outlet pressure corresponding to the supercharger is adjusted to preset supercharger reference pressure; and the group control assembly opens a supercharger gas supply valve of the supercharger after the supercharger outlet pressure reaches the supercharger reference pressure so as to supply gas to the gas using object. And the operation difficulty and the manual dependence degree during series gas supply are reduced.

Description

Technical Field

[0001] This application relates to the technical field of heavy gas turbine test technology, and particularly to a method for remotely and automatically controlling series gas supply of a centrifugal compressor. Background Art

[0002] During the component test of a heavy gas turbine, air compression and pressurization can be achieved through an air compressor and a booster. In this scenario, it is necessary to rely on staff to start the air compressor and the booster, and through a series of manual control operations, the gas supply of the air compressor and the booster is realized. The degree of manual dependence is relatively high, and there are certain operation difficulties and operation risks. Summary of the Invention

[0003] The purpose of this application aims to solve at least one of the technical problems in the above technologies to a certain extent.

[0004] A first aspect of this application provides a method for remotely and automatically controlling series gas supply of a centrifugal compressor, including an air compressor, a booster, an air compressor control component, a booster control component, and a group control component. Among them, through the group control component, after receiving a series gas supply instruction, the air compressor and the booster are controlled to enter a series preparation state, and after the air compressor and the booster enter the series preparation state, the medium-pressure gas supply valve between the air compressor and the booster is opened; through the air compressor control component, an air compressor start instruction sent by the group control component after the medium-pressure gas supply valve is opened is received to start the air compressor, and the inlet pressure of the booster is established through an inlet valve and an exhaust vent valve; through the booster control component, a booster start instruction sent by the group control component is received to start the booster, and the booster outlet pressure corresponding to the booster is adjusted to a preset booster reference pressure; after the booster outlet pressure reaches the booster reference pressure, the group control component opens the booster gas supply valve of the booster to supply gas to the gas-using object.

[0005] A method for remotely and automatically controlling series gas supply of a centrifugal compressor provided in the first aspect of this application also has the following technical features, including:

[0006] According to an embodiment of this application, the method further includes: through the group control component, when the air compressor starts, and the air compressor outlet pressure corresponding to the air compressor reaches a preset air compressor reference outlet pressure, and the air compressor outlet temperature of the air compressor reaches a preset air compressor reference outlet temperature, a booster start instruction is sent to the booster control component, where the air compressor reference outlet pressure is obtained based on the design pressure ratio of the booster and the booster reference outlet pressure.

[0007] According to an embodiment of the present application, the method further includes: through the supercharger control component, after the supercharger is started, adjusting the supercharger intake valve of the supercharger to the minimum working opening degree, and adjusting the supercharger anti-surge relief valve of the supercharger to adjust the supercharger outlet pressure to the supercharger reference outlet pressure.

[0008] According to an embodiment of the present application, after adjusting the supercharger outlet pressure to the supercharger reference outlet pressure, the method further includes: after the supercharger outlet pressure reaches the supercharger reference outlet pressure, in response to the fact that the air supply volume of the supercharger cannot meet the required air volume of the air-using object, the supercharger control component gradually closes the supercharger anti-surge relief valve; after the supercharger anti-surge relief valve is completely closed, in response to the fact that the air supply volume of the supercharger cannot meet the required air volume of the air-using object, the supercharger control component gradually adjusts the supercharger intake valve to the maximum working opening degree, and the air compressor control component gradually closes the air compressor anti-surge relief valve; after the supercharger anti-surge relief valve is completely closed and the supercharger intake valve is at the maximum working opening degree and the air compressor anti-surge relief valve is completely closed, in response to the fact that the series air supply volume of the air compressor and the supercharger cannot meet the required air volume, the air compressor control component continues to increase the air compressor intake valve.

[0009] According to an embodiment of the present application, the method further includes: through the central control component, sending the series start instruction to the group control component, and after receiving the series start instruction, the group control component sends a start preparation instruction to the air compressor control component and the supercharger control component; the air compressor control component and the supercharger control component enter the preparation state based on the start preparation instruction and return a start preparation completion signal to the group control component.

[0010] According to an embodiment of the present application, the group control component is further configured to, after receiving the start preparation completion signal, adjust the air compressor cold air valve, the air compressor hot air valve, and the air compressor air supply valve of the air compressor to a preset state; and adjust the supercharger cold air valve, the supercharger hot air valve, and the supercharger air supply valve of the supercharger to a preset supercharger valve preparation state to control the air supply system to enter the series preparation state.

[0011] According to an embodiment of the present application, the method further includes: when the air compressor and the booster are in a series medium-pressure air supply state, in response to the group control component receiving a low-pressure air supply instruction sent by the central control component, the group control component sends an unloading instruction to the booster control component, and the booster control component adjusts the booster to the unloading state based on the unloading instruction; after the booster enters the unloading state, the group control component sends a booster shutdown instruction to the booster control component, and the booster control component controls the booster to stop running based on the booster shutdown instruction; after the booster stops running, the group control component adjusts the booster air supply valve, the booster cold air valve, and the booster hot air valve to their initial states respectively.

[0012] According to an embodiment of the present application, after the booster control component controls the booster to stop running based on the booster shutdown instruction, it further includes: after the booster stops running, the air compressor control component adjusts the air compressor outlet pressure of the air compressor to a preset air compressor reference pressure value, and adjusts the air compressor cold air valve, the air compressor hot air valve, and the air compressor air supply valve of the air compressor to preset states respectively.

[0013] According to an embodiment of the present application, the method further includes: obtaining the air compressor outlet pressure value, the air compressor outlet air flow temperature, the booster inlet pressure value, the booster inlet air flow temperature, the booster outlet pressure value, and the main engine vibration parameters, etc. of the air compressor through the detection component.

[0014] According to an embodiment of the present application, in the series medium-pressure air supply state, the output of the air compressor is fixed to the cold air mode.

[0015] In the second aspect of the present application, a remotely automatic controlled series gas supply device for a centrifugal compressor is provided, including a first control module, a second control module, a third control module, and a gas supply module, where: The first control module is configured to, through the group control component, after receiving a series gas supply instruction, control the air compressor and the booster to enter a series preparation state, and after the air compressor and the booster enter the series preparation state, open the medium-pressure gas supply valve between the air compressor and the booster; The second control module is configured to, through the air compressor control component, receive the air compressor start instruction sent by the group control component after the medium-pressure gas supply valve is opened, so as to start the air compressor, and establish the inlet pressure of the booster through the intake valve and the exhaust vent valve; The third control module is configured to, through the booster control component, receive the booster start instruction sent by the group control component, so as to start the booster, and adjust the booster outlet pressure corresponding to the booster to a preset booster reference pressure; The gas supply module is configured to, after the booster outlet pressure reaches the booster reference pressure, the group control component opens the booster gas supply valve of the booster to supply gas to the gas-using object.

[0016] The remotely automatic controlled series gas supply method for a centrifugal compressor provided by the present application, based on the group control component, the air compressor control component, and the booster control component, controls the start and series connection of the air compressor and the booster, thereby realizing the gas supply to the gas-using object, reducing the operation difficulty and the degree of manual dependence when the air compressor and the booster supply gas, improving the accuracy and stability of the gas supply operation, and further improving the stability of the gas source supply for the gas-using object, optimizing the gas supply method and the gas supply effect based on the air compressor and the booster, and in the scenario of conducting heavy-duty gas turbine component tests based on compressed air, improving the test stability and the accuracy of the test results, and optimizing the test method and the test effect.

[0017] will become apparent from the description or will be partially given in the following description and will be partially learned from the practice below. Brief Description of the Drawings

[0018] The above and / or additional aspects and advantages of the present application will become apparent and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0019] Figure 1 is a schematic diagram of the remotely automatic controlled series gas supply method for a centrifugal compressor according to an embodiment of the present application;

[0020] Figure 2 is a schematic diagram of the remotely automatic controlled series gas supply method for a centrifugal compressor according to another embodiment of the present application;

[0021] Figure 3Schematic diagram of the centrifugal compressor remote automatic control series gas supply method according to another embodiment of the present application;

[0022] Figure 4 Schematic diagram of the centrifugal compressor remote automatic control series gas supply device according to an embodiment of the present application. Detailed implementation manners

[0023] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, but should not be construed as limiting the present application.

[0024] The centrifugal compressor remote automatic control series gas supply method according to the embodiment of the present application will be described below with reference to the accompanying drawings.

[0025] Figure 1 Schematic diagram of a gas supply system according to an embodiment of the present application, as Figure 1 shown, the gas supply system 100 includes an air compressor 11, a booster 12, an air compressor control component 13, a booster control component 14, and a group control component 15. Among them, the centrifugal compressor remote automatic control series gas supply method proposed in the present application is implemented based on the Figure 1 gas supply system 100 shown below.

[0026] Through the group control component 15, after receiving the series gas supply instruction, the air compressor 11 and the booster 12 are controlled to enter the series preparation state, and after the air compressor 11 and the booster 12 enter the series preparation state, the medium-pressure gas supply valve between the air compressor 11 and the booster 12 is opened.

[0027] Through the air compressor control component 13, the air compressor start instruction sent by the group control component 15 after the medium-pressure gas supply valve is opened is received to start the air compressor 11, and the inlet pressure of the booster is established through the inlet valve and the exhaust vent valve.

[0028] Through the booster control component 14, the booster start instruction sent by the group control component 15 is received to start the booster 12, and the booster outlet pressure corresponding to the booster 12 is adjusted to the preset booster reference pressure.

[0029] After the booster outlet pressure reaches the booster reference pressure, the group control component 15 opens the booster gas supply valve corresponding to the booster 12 to supply gas to the gas-consuming object.

[0030] In the embodiment of the present application, the gas supply system 100 for implementing the centrifugal compressor remote automatic control series gas supply method includes Figure 1The shown air compressor 11 and supercharger 12 achieve air supply to the air-using object through the series connection between the air compressor 11 and the supercharger 12.

[0031] Optionally, when there is a series connection requirement between the air compressor 11 and the supercharger 12, the group control component 15 can receive the corresponding series air supply instruction. After receiving the series air supply instruction, the group control component 15 can Figure 1 control the operation of the air compressor 11 through the shown air compressor control component 13, and Figure 1 control the operation of the supercharger 12 through the shown supercharger control component 14, so as to achieve the series connection of the air compressor 11 and the supercharger 12.

[0032] In the embodiment of the present application, the air compressor control component 13 can control the start and stop of the air compressor 11, as well as the opening and closing of the intake valve and the anti-surge relief valve used by the air compressor 11 respectively, and establish the supercharger inlet pressure through the intake valve and the exhaust relief valve. The supercharger control component 14 can control the start and stop of the supercharger 12, as well as the opening and closing of the intake valve and the anti-surge relief valve used by the supercharger 12 respectively. The group control component 15 can control the opening and closing of other remaining valves in the air supply system. Among them, these valves can include the cold air supply valve, the hot air supply valve, the main flow supply valve, the secondary flow supply valve, etc. of the air compressor 11 and the supercharger 12 respectively, and no specific limitation is made here.

[0033] In this scenario, after receiving the series air supply instruction, the group control component 15 can control the air compressor 11 and the supercharger 12 to enter a preset series preparation state. Among them, the group control component 15 can control the cold air supply valve, the hot air supply valve, the main flow supply valve, and the secondary flow supply valve of the air compressor 11 and the supercharger 12 to be adjusted to the preset preparation working opening respectively. It can be understood that when the cold air supply valve, the hot air supply valve, the main flow supply valve, and the secondary flow supply valve of the air compressor 11 and the supercharger 12 are adjusted to this preparation working opening respectively, it can be determined that the air compressor 11 and the supercharger 12 in this scenario have completed the preparation work before series air supply, and further, it can be determined that the air compressor 11 and the supercharger 12 have entered the series preparation state.

[0034] In the embodiment of the present application, after the air compressor 11 and the supercharger 12 enter the series preparation state, the group control component 15 can open the medium-pressure air supply valve between the air compressor 11 and the supercharger 12, and send an air compressor start instruction to the air compressor control component 13 after the medium-pressure air supply valve is opened. The air compressor control component 13 starts the operation of the air compressor 11 based on the received air compressor start instruction.

[0035] In this scenario, the operating state of the air compressor 11 can be obtained, and it can be identified whether the operating state of the air compressor 11 meets the operating conditions of the supercharger 12. Among them, when the group control component 15 identifies that the current operating state of the air compressor 11 meets the operating conditions of the supercharger 12, a supercharger start instruction can be sent to the supercharger control component 14, and the supercharger control component 14 starts the supercharger 12 to operate based on the received supercharger start instruction.

[0036] Optionally, when supplying gas to the gas-using object, there is a set pressure condition for the outlet air flow of the supercharger 12. In this scenario, after the supercharger 12 starts to operate, it is necessary to adjust the outlet air flow pressure of the gas supply valve position of the supercharger 12. Among them, the outlet air flow pressure of the supercharger 12 can be determined as the supercharger outlet pressure corresponding to the supercharger 12, and the pressure required to reach for the supercharger outlet pressure is set based on the pressure condition required during the gas supply of the gas-using object, as the supercharger reference pressure.

[0037] Furthermore, the supercharger control component 14 can adjust the supercharger outlet pressure through a preset pressure adjustment strategy so that the supercharger outlet pressure reaches the preset supercharger reference pressure. Among them, when the supercharger control component 14 adjusts the supercharger outlet pressure to the supercharger reference pressure, it can be determined that the current supercharger outlet pressure meets the pressure condition required for the gas supply of the gas-using object.

[0038] In this scenario, the group control component 15 can open the supercharger gas supply valve used when the supercharger 12 supplies gas, and supply gas to the gas-using object through the opening of the supercharger gas supply valve. Among them, the supercharger gas supply valve can be the main supercharger gas supply valve used by the supercharger 12, or the secondary supercharger gas supply valve used by the supercharger 12, which is determined according to the actual use requirements and is not specifically limited here.

[0039] The centrifugal compressor remote automatic control series gas supply method proposed in this application includes an air compressor, a booster, an air compressor control component, a booster control component, and a group control component. Among them, through the group control component, after receiving the series gas supply instruction, the air compressor and the booster are controlled to enter the series preparation state, and after the air compressor and the booster enter the series preparation state, the medium-pressure gas supply valve between the air compressor and the booster is opened; through the air compressor control component, the air compressor start instruction sent by the group control component after the medium-pressure gas supply valve is opened is received to start the air compressor; through the booster control component, the booster start instruction sent by the group control component is received to start the booster, and the booster outlet pressure corresponding to the booster is adjusted to the preset booster reference pressure; after the booster outlet pressure reaches the booster reference pressure, the group control component opens the booster gas supply valve of the booster to supply gas to the gas-consuming object. In this application, based on the group control component, the air compressor control component, and the booster control component, the start and series connection of the air compressor and the booster are controlled, so as to realize the gas supply to the gas-consuming object, reduce the operation difficulty and manual dependence degree when the air compressor and the booster supply gas, improve the gas supply operation accuracy and stability, and further improve the stability of the gas source supply of the gas-consuming object, optimize the gas supply method and gas supply effect based on the air compressor and the booster, and improve the test stability and the accuracy of the test results in the scenario of conducting gas turbine component tests based on compressed air, and optimize the test method and test effect.

[0040] In the above embodiment, regarding the gas supply to the gas-consuming object realized based on the air compressor and the booster, it can also be combined with Figure 2 understanding, Figure 2 which is a schematic diagram of the gas supply system according to another embodiment of this application. As Figure 2 shown, the gas supply system 200 includes an air compressor 21, a booster 22, an air compressor control component 23, a booster control component 24, a group control component 25, a central control component 26, and a detection component 27. Among them, the centrifugal compressor remote automatic control series gas supply method proposed in the embodiment of this application can be realized based on the gas supply system shown in Figure 2 and Figure 3 shown.

[0041] Optionally, through the central control component 26, the series start instruction is sent to the group control component 25. After receiving the series start instruction, the group control component 25 sends the start preparation instruction to the air compressor control component 23 and the booster control component 24. The air compressor control component 23 and the booster control component 24 enter the preparation state based on the start preparation instruction and return the start preparation completion signal to the group control component 25.

[0042] In the embodiments of the present application, the staff can send relevant control instructions to the group control component 25 through the central control component 26. In this scenario, the central control component 26 can receive the control instruction for the series gas supply of the air compressor and the booster sent by the staff, so as to realize the series gas supply of the air compressor 21 and the booster 22 to the gas-using object, and this instruction can be marked as the series start instruction received by the central control component 26.

[0043] In this scenario, after the central control component 26 receives the series start instruction sent by the staff, it can transmit the series start instruction to the group control component 25. After the group control component 25 receives the series start instruction, it can send the start preparation instruction corresponding to the air compressor 21 to the air compressor control component 23, and send the start preparation instruction corresponding to the booster 22 to the booster control component 24.

[0044] Further, after the air compressor control component 23 receives the start preparation instruction, it can adjust the relevant state of the air compressor 21 so that the air compressor 21 enters the preparatory state before starting. After the air compressor 21 enters the preparatory state before starting, the air compressor control component 23 can return the start preparation completion signal of the air compressor 21 to the group control component 25. And, after the booster control component 24 receives the start preparation instruction, it can adjust the relevant state of the booster 22 so that the booster 22 enters the preparatory state before starting. After the booster 22 enters the preparatory state before starting, the booster control component 24 can return the start preparation completion signal of the booster 22 to the group control component 25.

[0045] Optionally, through the group control component 25, after receiving the start preparation completion signal, the air compressor cold air valve, the air compressor hot air valve and the air compressor gas supply valve of the air compressor 21 are adjusted to the preset state. And, the booster cold air valve, the booster hot air valve and the booster gas supply valve of the booster 22 are adjusted to the preset booster valve preparatory state to control the gas supply system 200 to enter the series preparatory state.

[0046] In the embodiments of the present application, after the group control component 25 receives the start preparation completion signals respectively returned by the air compressor control component 23 and the booster control component 24, it can adjust the external valves respectively used by the air compressor 21 and the booster 22, so that the gas supply system 200 enters the series preparatory state of series gas supply.

[0047] As an example, as Figure 3 shown, after the group control component (not shown in the figure) receives the start preparation completion signals respectively returned by the air compressor control component (not shown in the figure) and the booster control component (not shown in the figure), the group control component (not shown in the figure) can Figure 3The 3 cold air supply valves and 5 cold air supply valves shown as the cold air valves of the air compressor, the 9 hot air supply valves shown as the hot air valves of the air compressor, and the 6 main stream supply valves and 7 secondary stream supply valves shown as the air supply valves of the air compressor are respectively adjusted to the preset preliminary states.

[0048] And, the group control component (not shown in the figure) can Figure 3 The 15 cold air supply valves and 17 cold air supply valves shown as the cold air valves of the supercharger, the 18 hot air supply valves shown as the hot air valves of the supercharger, and the 20 main stream supply valves and 21 secondary stream supply valves shown as the air supply valves of the supercharger are respectively adjusted to the preset preliminary states.

[0049] Further, based on the above adjustments, Figure 3 The shown air supply system enters the series preliminary state of series air supply.

[0050] Optionally, through the group control component 25, when the air compressor 21 starts, and the air compressor outlet pressure corresponding to the air compressor 21 reaches the preset air compressor reference outlet pressure, and the air compressor outlet temperature of the air compressor 21 reaches the preset air compressor reference outlet temperature, a start command for the supercharger 22 is sent to the supercharger control component 24, where the air compressor reference outlet pressure is obtained based on the design pressure ratio of the supercharger 22 and the supercharger reference outlet pressure.

[0051] In the embodiment of the present application, after the air compressor 21 starts, the group control component 25 can adjust the operation of the air compressor 21, so that the operation state of the air compressor 21 meets the operation start conditions of the supercharger 22.

[0052] It should be noted that in the embodiment of the present application, in the series medium-pressure air supply state, there are certain requirements for the intake temperature of the supercharger 22. In this scenario, the output of the air compressor 21 can be fixed to the cold air mode. It can be understood that by controlling the temperature of the output air flow by the air cooler of the air compressor 21 not to exceed the limit value, the requirements for the operation of the supercharger 22 are met in the scenario of series air supply between the air compressor 21 and the supercharger 22.

[0053] As an example, as Figure 3 shown, the group control component (not shown in the figure) can be based on Figure 3 the shown 2 pressure detection points to Figure 3 detect the outlet pressure of the shown 322 air compressor, obtain the air compressor outlet pressure corresponding to the 322 air compressor, and detect the outlet temperature of the 322 air compressor through a preset air compressor outlet temperature detection point (not shown in the figure), and obtain the air compressor outlet temperature of the 322 air compressor.

[0054] When the group control component (not shown in the figure) detects that the air compressor outlet pressure of the 322 air compressor reaches the preset air compressor reference outlet pressure and the air compressor outlet temperature corresponding to the 322 air compressor reaches the preset air compressor reference outlet temperature, it can be determined that Figure 3 the operating state of the 322 air compressor shown satisfies Figure 3 the start-up operating conditions of the 323 supercharger shown. In this scenario, the group control component can send a supercharger start command to Figure 3 the supercharger control component (not shown in the figure) corresponding to the 323 supercharger shown, so that the 323 supercharger can start running.

[0055] It should be noted that the air compressor reference outlet pressure and air compressor reference outlet temperature corresponding to the air compressor 21 can be set based on the start-up operating conditions of the supercharger 22. Among them, for the air compressor outlet reference pressure, it can be obtained based on the following formula:

[0056]

[0057] In the above formula, P1 represents the air compressor reference outlet pressure corresponding to the air compressor 21, P2 represents the supercharger reference outlet pressure corresponding to the supercharger 22, and k represents the design pressure ratio of the supercharger 22.

[0058] Optionally, through the supercharger control component 24, after the supercharger 22 starts, the supercharger intake valve of the supercharger 22 is adjusted to the minimum working opening, and the supercharger anti-surge vent valve of the supercharger 22 is adjusted to adjust the supercharger outlet pressure to the supercharger reference outlet pressure.

[0059] As an example, as Figure 3 shown, after the 323 supercharger shown starts, the group control component (not shown in the figure) can obtain the supercharger outlet pressure corresponding to the 323 supercharger through Figure 3 the 14 pressure detection points shown. Figure 3

[0060] Among them, when the supercharger outlet pressure detected by the group control component (not shown in the figure) does not reach the preset supercharger reference outlet pressure, the 13 intake valve of the supercharger intake valve used as the 323 supercharger can be adjusted to the minimum working opening through the supercharger control component (not shown in the figure), and the 19 anti-surge vent valve of the supercharger anti-surge vent valve used as the 323 supercharger can be closed to the preset anti-surge vent valve working opening through the supercharger control component (not shown in the figure) to adjust the supercharger outlet pressure corresponding to the 323 supercharger until the outlet pressure corresponding to the 323 supercharger reaches the preset supercharger reference outlet pressure.

[0061] ​It should be noted that the working opening adjustment of the supercharger control component (not shown in the figure) for the 19 anti-surge vent valve in the above content can be a dynamic working opening adjustment. It can be understood that the group control component (not shown in the figure) obtains the supercharger outlet pressure corresponding to the 323 supercharger in real time based on the 14 pressure detection points, and the supercharger control component (not shown in the figure) adjusts the working opening of the 19 anti-surge vent valve based on the real-time supercharger outlet pressure detected by the group control component (not shown in the figure), until the real-time supercharger outlet pressure of the 323 supercharger detected by the group control component (not shown in the figure) reaches the preset supercharger reference outlet pressure, and the supercharger control component (not shown in the figure) can stop adjusting the working opening of the 19 anti-surge vent valve.

[0062] Optionally, after the outlet pressure of the supercharger 22 reaches the supercharger reference outlet pressure, in response to the gas supply volume of the supercharger 22 being unable to meet the required gas volume of the gas-using object, the supercharger control component 24 closes the supercharger anti-surge vent valve.

[0063] In the embodiment of the present application, when the supercharger outlet pressure reaches the supercharger reference outlet pressure, the gas supply volume of the supercharger 22 when supplying gas based on this supercharger outlet pressure may be unable to meet the required gas volume of the gas-using object. In this scenario, it is necessary to further adjust the supercharger outlet pressure so that the gas supply volume of the supercharger 22 when supplying gas based on the adjusted supercharger outlet pressure can meet the required gas volume of the gas-using object.

[0064] As an example, as Figure 3 shown, when the gas supply volume realized based on the supercharger outlet pressure is unable to meet the required gas volume of the gas-using object, the supercharger control component (not shown in the figure) can control Figure 3 the 19 anti-surge vent valve shown to close, thereby increasing the supercharger outlet pressure of the 323 supercharger, and further enabling the gas supply volume of the 323 supercharger after closing the 19 anti-surge vent valve to meet the required gas volume of the gas-using object.

[0065] Optionally, after the supercharger anti-surge vent valve is closed, in response to the gas supply volume of the supercharger 22 being unable to meet the required gas volume of the gas-using object, the supercharger control component 24 gradually adjusts the supercharger intake valve to the maximum working opening, and the air compressor control component 23 closes the air compressor anti-surge vent valve.

[0066] In the embodiment of the present application, after the supercharger anti-surge vent valve is closed, the gas supply volume of the supercharger 22 realized based on the adjusted supercharger outlet pressure may still be unable to meet the required gas volume of the gas-using object. In this scenario, the intake valve of the supercharger 22 and the relevant valves of the air compressor 21 can also be adjusted to continue adjusting the supercharger outlet pressure of the supercharger 22.

[0067] As an example, as Figure 3 shown, when the gas supply volume of the booster compressor after the 19 anti-surge vent valve is closed cannot meet the required gas volume of the gas-consuming object, the booster compressor control component (not shown in the figure) can continue to adjust Figure 3 the opening of the intake valve of the intake valve 13 of the booster compressor shown.

[0068] When the intake valve is adjusted to the maximum working opening, the outlet pressure of the air compressor of the 322 air compressor may drop. In this scenario, the air compressor control component (not shown in the figure) can control the 10 anti-surge vent valve corresponding to the 322 air compressor to close, so as to reduce the impact of the opening of the 13 intake valve on the reduction of the outlet pressure of the air compressor.

[0069] Furthermore, based on the closing of the anti-surge vent valve of the booster compressor, the opening of the intake valve of the booster compressor, and the closing of the anti-surge vent valve of the air compressor, the outlet pressure of the booster compressor is increased, so that the gas supply volume corresponding to the increased outlet pressure of the booster compressor can meet the required gas volume of the gas-consuming object.

[0070] Optionally, after the anti-surge vent valve of the booster compressor is closed, the intake valve of the booster compressor is adjusted to the maximum working opening, and the anti-surge vent valve of the air compressor is closed, in response to the series gas supply volume of the air compressor 21 and the booster compressor 22 being unable to meet the required gas volume, the air compressor control component 23 opens the intake valve of the air compressor.

[0071] In the embodiment of the present application, when the anti-surge vent valve of the booster compressor is closed, the intake valve of the booster compressor is adjusted to the maximum working opening, and the anti-surge vent valve of the air compressor is closed, it can be understood that the air compressor 21 and the booster compressor 22 in this scenario have realized series gas supply to the gas-consuming object.

[0072] When the series gas supply volume of the air compressor 21 and the booster compressor 22 to the gas-consuming object in this scenario still cannot meet the required gas volume of the gas-consuming object, relevant adjustments can be made to the air compressor 21 to achieve the purpose of increasing the outlet pressure of the booster compressor.

[0073] As an example, as Figure 3 shown, in the scenario where the 19 anti-surge vent valve is closed, the 13 intake valve is adjusted to the maximum working opening, and the 10 anti-surge vent valve is closed, when the series gas supply volume of the booster compressor and the air compressor cannot meet the required gas volume of the gas-consuming object, the air compressor control component (not shown in the figure) can open the 1 intake valve to increase the outlet pressure of the air compressor of the 322 air compressor, thereby increasing the outlet pressure of the 323 booster compressor, so that the gas supply volume realized based on the increased outlet pressure of the booster compressor can meet the required gas volume of the gas-consuming object.

[0074] Optionally, when the air compressor 21 and the supercharger 22 are in a series medium-pressure air supply state, in response to the group control component 25 receiving the low-pressure air supply instruction sent by the central control component 26, the group control component 25 sends an unloading instruction to the supercharger control component 24, and the supercharger control component 24 adjusts the supercharger 22 to the unloading state based on the unloading instruction.

[0075] In the embodiment of the present application, when the air compressor 21 and the supercharger 22 supply air in series to the air-using object, the required air pressure of the air-using object may decrease. In this scenario, the staff can send a low-pressure air supply instruction to the central control component 26, so that the air supply system 200 reduces the air supply pressure through this low-pressure air supply instruction, reducing the power consumption of the supercharger unit.

[0076] Among them, the central control component 26 can send a low-pressure air supply instruction to the group control component 25. After the group control component 25 receives the low-pressure air supply instruction sent by the central control component 26, it can send an operation instruction related to controlling the supercharger 22 to exit the series air supply to the supercharger control component 24. Among them, this operation instruction can be determined as the unloading instruction sent by the group control component 25 to the supercharger control component 24.

[0077] Further, after the supercharger control component 24 receives the unloading instruction, it can adjust the supercharger 22 and the related valves of the supercharger 22 to make the supercharger 22 exit the series medium-pressure air supply state with the air compressor.

[0078] As an example, as Figure 3 shown, after the group control component (not shown in the figure) receives the low-pressure air supply instruction, it can send the unloading instruction corresponding to the supercharger to the supercharger control component (not shown in the figure). After the supercharger control component (not shown in the figure) receives the unloading instruction, it can Figure 3 adjust the 13 intake valve shown to its corresponding preset working opening, and adjust the Figure 3 19 anti-surge relief valve shown to its corresponding preset working opening.

[0079] It can be understood that when the 13 intake valve is adjusted to its corresponding preset working opening and the 19 anti-surge relief valve is adjusted to its corresponding preset working opening, it can be determined that the 13 intake valve and the 19 anti-surge relief valve are in the unloading state. In this scenario, these two preset working openings can be respectively marked as the preset unloading working opening of the 13 intake valve and the preset unloading working opening of the 19 anti-surge relief valve.

[0080] In this scenario, the supercharger control component (not shown in the figure) can make the 323 supercharger enter the unloading state by adjusting the 13 intake valve and the 19 anti-surge relief valve to their respective unloading working openings.

[0081] Optionally, after the booster 22 enters the unloaded state, the group control component 25 sends a booster shutdown instruction to the booster control component 24, and the booster control component 24 controls the booster 22 to stop running based on the booster shutdown instruction.

[0082] In the embodiment of the present application, after the booster control component 24 adjusts the booster 22 to enter the unloaded state, relevant response information can be returned to the group control component 25. After receiving this information, the group control component 25 can send a stop instruction for the booster 22 to the booster control component 24.

[0083] In this scenario, the booster control component 24 can control the booster 22 to stop running based on the received booster shutdown instruction to achieve the shutdown of the booster 22, so that the booster 22 exits the state of supplying gas in series with the air compressor 21.

[0084] It should be noted that after the booster 22 stops running, the pressure measurement point corresponding to the air compressor 21 can be adjusted from the relevant position at the air inlet of the booster 22 to the relevant position at the air outlet of the air compressor 21, and no specific limitation is made here.

[0085] Optionally, after the booster 22 stops running, the group control component 25 adjusts the booster gas supply valve, the booster cold gas valve, and the booster hot gas valve to their preset states respectively.

[0086] As an example, as Figure 3 shown, after the 323 booster stops running, the group control component (not shown in the figure) can Figure 3 adjust the 20 main gas supply valve and the 21 secondary gas supply valve shown as the booster gas supply valve, Figure 3 the 15 cold gas supply valve and the 17 cold gas supply valve shown as the booster cold gas valve, and Figure 3 the 18 hot gas supply valve shown as the booster hot gas valve to their respective preset states. Among them, this state can be the initial state set for each valve or other preset states for each valve, and no specific limitation is made here.

[0087] As Figure 2 shown, the gas supply system 200 proposed in the present application further includes Figure 2 the detection component 27 shown. Among them, through the detection component 27, the air compressor outlet pressure value, the air compressor outlet air flow temperature, the booster inlet pressure value, the booster inlet air flow temperature, the booster outlet pressure value, and the main engine vibration parameters of the air compressor 21 are obtained.

[0088] In the embodiments of the present application, through the setting of the detection component 27 in the air supply system 200, the detection of relevant parameters of the air compressor 21 and the supercharger 22 can be realized. Among them, corresponding temperature detection points and pressure detection points can be set at relevant positions at the outlet of the air compressor 21 through the detection component 27, so as to detect the pressure parameter and temperature parameter at the outlet of the air compressor 21, and then determine the air compressor outlet pressure value and the air compressor outlet air flow temperature of the air compressor 21 obtained by the detection as the pressure parameter and temperature parameter.

[0089] Correspondingly, by setting pressure parameter detection points and temperature parameter detection points at relevant positions at the inlet and outlet of the supercharger 22 through the detection component 27 respectively, relevant pressure parameters and temperature parameters at the inlet position of the supercharger 22, and relevant pressure parameters and temperature parameters at the outlet position of the supercharger can be obtained. Among them, the pressure parameter and temperature parameter detected at the inlet position of the supercharger detected can be determined as the supercharger inlet pressure value and the supercharger inlet air flow temperature of the supercharger 22 respectively, and the pressure parameter at the outlet position of the supercharger detected can be determined as the supercharger outlet pressure value of the supercharger 22.

[0090] In addition, through the deployment of the detection component 27, the vibration parameters of the main engine can be collected, so as to obtain the main engine vibration parameters.

[0091] As an example, as Figure 3 shown, based on the setting of the detection component (not shown in the figure), through Figure 3 the 2 pressure detection points shown, the air compressor outlet pressure value of the 322 air compressor can be obtained, and through Figure 3 the 11 pressure detection points shown, the supercharger inlet pressure value of the 323 supercharger can be obtained, and through Figure 3 the 12 temperature detection points shown, the supercharger inlet air flow temperature of the 323 supercharger can be obtained, and through Figure 3 the 14 pressure detection points shown, the supercharger outlet pressure value of the 323 supercharger can be obtained.

[0092] Optionally, after the supercharger 22 stops running, the air compressor control component 23 adjusts the air compressor outlet pressure of the air compressor 21 to a preset air compressor reference pressure value, and adjusts the air compressor cold air valve, the air compressor hot air valve and the air compressor air supply valve of the air compressor 21 to preset states respectively.

[0093] In the embodiments of the present application, when the supercharger 22 stops running, the air supply system 200 enters the state of the air compressor 21 supplying air alone. In this scenario, the relevant state of the air compressor 21 can be adjusted so that the air compressor 21 can still supply air to the air-using object after exiting the scenario of supplying air in series with the supercharger.

[0094] As an example, as Figure 3 shown, after the 323 supercharger stops running, the air compressor control component (not shown in the figure) can obtain the air compressor outlet pressure value of the air compressor from the Figure 3 2 pressure detection points shown, and after obtaining this pressure value, the air compressor control component (not shown in the figure) can adjust this pressure value to the preset air compressor reference pressure value.

[0095] In addition, the air compressor control component (not shown in the figure) can Figure 3 adjust the 3 cold air supply valves and 5 cold air supply valves, which are the cold air supply valves of the air compressor shown, to their respective preset states, and Figure 3 adjust the 9 hot air supply valves, which are the hot air supply valves of the air compressor shown, to their corresponding preset states, and Figure 3 adjust the 6 main flow supply valves and 7 secondary flow supply valves, which are the flow supply valves of the air compressor shown, to their respective preset states.

[0096] In this example, based on the above adjustments made by the air compressor control component (not shown in the figure), the cold air supply valve, hot air supply valve, and air supply valve of the air compressor can enter the valve states required for separate air supply, thereby realizing the state switch of the air compressor from series air supply with the supercharger to separate air supply to the gas-using object.

[0097] The centrifugal compressor remote automatic control series air supply method proposed in this application, based on the group control component, air compressor control component, and supercharger control component, controls the start and series connection of the air compressor and the supercharger, thereby realizing the air supply to the gas-using object, reducing the operation difficulty and manual dependence degree when the air compressor and the supercharger supply air, improving the air supply operation accuracy and stability, and further improving the stability of the gas source supply of the gas-using object, optimizing the air supply method and air supply effect based on the air compressor and the supercharger, and improving the test stability and optimizing the test method and test effect in the scenario of conducting gas turbine component tests based on compressed air.

[0098] An embodiment of this application also proposes a centrifugal compressor remote automatic control series air supply device. Since the centrifugal compressor remote automatic control series air supply device proposed in the embodiment of this application corresponds to the centrifugal compressor remote automatic control series air supply methods proposed in the above several embodiments, the implementation manners of the above centrifugal compressor remote automatic control series air supply methods are also applicable to the centrifugal compressor remote automatic control series air supply device proposed in the embodiment of this application, and will not be described in detail in the following embodiments.

[0099] Figure 4Schematic diagram of a centrifugal compressor remote automatic control series gas supply device according to an embodiment of the present application, as shown in Figure 4 shown, the centrifugal compressor remote automatic control series gas supply device 400 includes a first control module 41, a second control module 42, a third control module 43, a gas supply module 44, and a fourth control module 45, where:

[0100] The first control module 41 is configured to, through the group control component, after receiving the series gas supply instruction, control the air compressor and the booster to enter the series preparation state, and after the air compressor and the booster enter the series preparation state, open the medium-pressure gas supply valve between the air compressor and the booster;

[0101] The second control module 42 is configured to, through the air compressor control component, receive the air compressor start instruction sent by the group control component after the medium-pressure gas supply valve is opened, so as to start the air compressor, and establish the booster inlet pressure through the intake valve and the exhaust vent valve;

[0102] The third control module 43 is configured to, through the booster control component, receive the booster start instruction sent by the group control component, so as to start the booster, and adjust the booster outlet pressure corresponding to the booster to a preset booster reference pressure;

[0103] The gas supply module 44 is configured to, after the booster outlet pressure reaches the booster reference pressure, open the booster gas supply valve of the booster to supply gas to the gas-consuming object.

[0104] In the embodiment of the present application, the first control module 41 is further configured to: through the group control component, when the air compressor starts, and the air compressor outlet pressure corresponding to the air compressor reaches the preset air compressor reference outlet pressure, and the air compressor outlet temperature of the air compressor reaches the preset air compressor reference outlet temperature, send a booster start instruction to the booster control component, where the air compressor reference outlet pressure is obtained based on the design pressure ratio of the booster and the booster reference outlet pressure.

[0105] In the embodiment of the present application, the third control module 43 is further configured to: through the booster control component, after the booster starts, adjust the booster intake valve of the booster to the minimum working opening, and adjust the booster anti-surge vent valve of the booster to adjust the booster outlet pressure to the booster reference outlet pressure.

[0106] In an embodiment of the present application, the third control module 43 is further configured to: after the outlet pressure of the supercharger reaches the reference outlet pressure of the supercharger, in response to the gas supply volume of the supercharger being unable to meet the required gas volume of the gas-consuming object, the supercharger control assembly gradually closes the anti-surge vent valve of the supercharger; after the anti-surge vent valve of the supercharger is completely closed, in response to the gas supply volume of the supercharger being unable to meet the required gas volume of the gas-consuming object, the supercharger control assembly gradually adjusts the intake valve of the supercharger to the maximum working opening, and the air compressor control assembly gradually closes the anti-surge vent valve of the air compressor; after the anti-surge vent valve of the supercharger is completely closed, the intake valve of the supercharger is at the maximum working opening, and the anti-surge vent valve of the air compressor is completely closed, in response to the series gas supply volume of the air compressor and the supercharger being unable to meet the required gas volume, the air compressor control assembly continues to increase the intake valve of the air compressor.

[0107] In an embodiment of the present application, the method further includes a fourth control module 45, configured to: send a series start instruction to the group control assembly through the central control assembly, and after receiving the series start instruction, the group control assembly sends a start preparation instruction to the air compressor control assembly and the supercharger control assembly; the air compressor control assembly and the supercharger control assembly enter a preparatory state based on the start preparation instruction and return a start preparation completion signal to the group control assembly.

[0108] In an embodiment of the present application, the fourth control module 45 is further configured to: through the group control assembly, after receiving the start preparation completion signal, adjust the cold air valve, the hot air valve, and the air supply valve of the air compressor to a preset state; and adjust the cold air valve, the hot air valve, and the air supply valve of the supercharger to a preset supercharger valve preparatory state to control the gas supply system to enter a series preparatory state.

[0109] In an embodiment of the present application, the first control module 41 is further configured to: when the air compressor and the supercharger are in a series medium-pressure gas supply state, in response to the group control assembly receiving a low-pressure gas supply instruction sent by the central control assembly, the group control assembly sends an unloading instruction to the supercharger control assembly, and the supercharger control assembly adjusts the supercharger to an unloading state based on the unloading instruction; after the supercharger enters the unloading state, the group control assembly sends a supercharger shutdown instruction to the supercharger control assembly, and the supercharger control assembly controls the supercharger to stop running based on the supercharger shutdown instruction; after the supercharger stops running, the group control assembly adjusts the supercharger air supply valve, the supercharger cold air valve, and the supercharger hot air valve to their initial states respectively.

[0110] In an embodiment of the present application, the second control module 42 is further configured to: after the supercharger stops running, the air compressor control assembly adjusts the outlet pressure of the air compressor to a preset air compressor reference pressure value, and adjusts the cold air valve, the hot air valve, and the air supply valve of the air compressor to preset states respectively.

[0111] In the embodiments of the present application, the device further includes a detection module, configured to: obtain the air compressor outlet pressure value, air compressor outlet air flow temperature, supercharger inlet pressure value, supercharger inlet air flow temperature, supercharger outlet pressure value, and main engine vibration parameters of the air compressor through a detection component, etc.

[0112] In the embodiments of the present application, in the series medium-pressure gas supply state, the output of the air compressor is fixed to the cold air mode.

[0113] The centrifugal compressor remote automatic control series gas supply device provided by the present application controls the start and series connection of the air compressor and the supercharger based on the group control component, the air compressor control component, and the supercharger control component, so as to realize the gas supply to the gas-consuming object, reduce the operation difficulty and manual dependence degree when the air compressor and the supercharger supply gas, improve the gas supply operation accuracy and stability, and further improve the stability of the gas source supply of the gas-consuming object, optimize the gas supply method and gas supply effect based on the air compressor and the supercharger to realize gas supply, and improve the test stability, optimize the test method and test effect in the scenario of heavy gas turbine component tests based on compressed air.

[0114] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0115] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0116] It should not be understood as a limitation to the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A remote automatic control series gas supply method for a centrifugal compressor, characterized in that It includes an air compressor, a supercharger, an air compressor control component, a supercharger control component and a group control component. Among them, Through the group control component, after receiving the series gas supply instruction, it controls the air compressor and the supercharger to enter the series preparation state, and after the air compressor and the supercharger enter the series preparation state, it opens the medium-pressure gas supply valve between the air compressor and the supercharger; Through the air compressor control component, it receives the air compressor start instruction sent by the group control component after the medium-pressure gas supply valve is opened to start the air compressor, and establishes the supercharger inlet pressure through the intake valve and the exhaust vent valve; Through the supercharger control component, it receives the supercharger start instruction sent by the group control component to start the supercharger, and adjusts the supercharger outlet pressure corresponding to the supercharger to the preset supercharger reference pressure; After the supercharger outlet pressure reaches the supercharger reference pressure, the group control component opens the supercharger gas supply valve of the supercharger to supply gas to the gas-using object.

2. The method according to claim 1, characterized in that The method further includes: Through the group control component, when the air compressor starts, and the air compressor outlet pressure corresponding to the air compressor reaches the preset air compressor reference outlet pressure, and the air compressor outlet temperature of the air compressor reaches the preset air compressor reference outlet temperature, it sends the supercharger start instruction to the supercharger control component, where the air compressor reference outlet pressure is obtained based on the design pressure ratio of the supercharger and the supercharger reference outlet pressure.

3. The method according to claim 2, wherein The method further includes: Through the supercharger control component, after the supercharger starts, it adjusts the supercharger intake valve to the minimum working opening degree, and adjusts the supercharger anti-surge vent valve to adjust the supercharger outlet pressure to the supercharger reference outlet pressure.

4. The method according to claim 3, characterized in that, After adjusting the supercharger outlet pressure to the supercharger reference outlet pressure, it further includes: After the supercharger outlet pressure reaches the supercharger reference outlet pressure, in response to the fact that the gas supply volume of the supercharger cannot meet the required gas volume of the gas-using object, the supercharger control component gradually closes the supercharger anti-surge vent valve; After the supercharger anti-surge vent valve is completely closed, in response to the fact that the gas supply volume of the supercharger cannot meet the required gas volume of the gas-using object, the supercharger control component gradually adjusts the supercharger intake valve to the maximum working opening degree, and the air compressor control component gradually closes the air compressor anti-surge vent valve; After the supercharger anti-surge vent valve is completely closed, the supercharger intake valve is at the maximum working opening degree, and the air compressor anti-surge vent valve is completely closed, in response to the fact that the series gas supply volume of the air compressor and the supercharger cannot meet the required gas volume, the air compressor control component continues to increase the air compressor intake valve.

5. The method according to claim 1, characterized in that The method further includes: Through the central control component, it sends the series start instruction to the group control component. After receiving the series start instruction, the group control component sends the start preparation instruction to the air compressor control component and the supercharger control component; The air compressor control component and the supercharger control component enter the standby state based on the startup preparation instruction and return a startup preparation completion signal to the group control component.

6. The method according to claim 5, wherein After the air compressor control component and the supercharger control component enter the standby state based on the startup preparation instruction and return a startup preparation completion signal to the group control component, the following steps are further included: Through the group control component, after receiving the startup preparation completion signal, the air compressor cold air valve, the air compressor hot air valve, and the air compressor supply valve of the air compressor are adjusted to preset states. And the supercharger cold air valve, the supercharger hot air valve, and the supercharger supply valve of the supercharger are adjusted to a preset supercharger valve standby state to control the gas supply system to enter the series standby state.

7. The method according to any one of claims 1-6, characterized in that, The method further includes: When the air compressor and the supercharger are in the series medium-pressure gas supply state, in response to the group control component receiving a low-pressure gas supply instruction sent by the central control component, the group control component sends an unloading instruction to the supercharger control component, and the supercharger control component adjusts the supercharger to the unloading state based on the unloading instruction. After the supercharger enters the unloading state, the group control component sends a supercharger shutdown instruction to the supercharger control component, and the supercharger control component controls the supercharger to stop running based on the supercharger shutdown instruction. After the supercharger stops running, the group control component adjusts the supercharger supply valve, the supercharger cold air valve, and the supercharger hot air valve to their initial states respectively.

8. The method according to claim 7, wherein After the supercharger control component controls the supercharger to stop running based on the supercharger shutdown instruction, the following steps are further included: After the supercharger stops running, the air compressor control component adjusts the air compressor outlet pressure of the air compressor to a preset air compressor reference pressure value, and adjusts the air compressor cold air valve, the air compressor hot air valve, and the air compressor supply valve of the air compressor to preset states respectively.

9. The method according to any one of claims 1-6 and / or 8, characterized in that, The method further includes: Through the detection component, obtain the air compressor outlet pressure value, the air compressor outlet air flow temperature, the supercharger inlet pressure value, the supercharger inlet air flow temperature, the supercharger outlet pressure value, and the main engine vibration parameters of the air compressor, etc.

10. The method according to any one of claims 1-6 and / or 8, characterized in that, In the series medium-pressure gas supply state, the output of the air compressor is fixed to the cold air mode.

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