A safety interlocking method for large-scale cryogenic axial compressors

Abstract

The present invention provides a safety interlocking method for a large-size deep-cryogenic axial flow compressor, which mainly relates to the field of safe operation protection of large-scale rotating mechanical equipment, and adopts 90s deceleration shutdown, 15s emergency braking, emergency shutdown and free shutdown interlocking shutdown mode, wherein the 15s emergency braking has the highest priority, but when emergency shutdown is concurrent, only emergency shutdown mode can be used for shutdown. By setting a variety of shutdown modes, the interlocking shutdown requirements of deep-cryogenic axial flow compressors under different safety conditions can be met.

Description

Technical Field

[0001] The present invention mainly relates to the field of safety operation protection for large rotating mechanical equipment, and particularly relates to a safety interlock method for a large-size cryogenic axial compressor. Background Art

[0002] Large rotating mechanical equipment includes ventilators, blowers, compressors, steam turbines, generators, etc., and is widely used in many fields such as national economic construction in petroleum, chemical industry, metallurgy, etc. Among them, axial compressors have outstanding advantages such as strong flow capacity and high efficiency, and are particularly suitable for industrial occasions with large-flow requirements. Most of these industrial occasions are at ambient temperature, and axial compressors mostly operate under normal temperature, high temperature or shallow cryogenic conditions. Among them, the ethylene cryogenic axial compressor has the lowest operating temperature, which can only reach about 158K. Previously, there was no large-size cryogenic axial compressor in China with the ability to operate at a cryogenic temperature below 158K and put into practical engineering applications. Therefore, most of the existing safety operation protection technologies are for normal temperature or cryogenic axial compressors operating at temperatures above 158K, lacking a safety interlock method that meets the operating requirements of large-size cryogenic axial compressors at a cryogenic temperature of 110K and below.

[0003] A large number of large scientific projects and installations have been put into construction, commissioning and operation. The large-size cryogenic axial compressor is the key core equipment of a certain large scientific project and installation. By compressing gas to increase the outlet gas pressure, it provides operating power for the large scientific project and installation. Large-size cryogenic axial compressors with special application requirements have been developed as power sources for large scientific projects and installations. Low-temperature nitrogen gas after the vaporization of 77K cryogenic liquid nitrogen is used as the working medium, and the temperature range covers normal temperature 300K to 77K cryogenic temperature, and it will operate in a 110K cryogenic environment for a long time. Thus, the main body equipment such as the casing and shafting of this large-size cryogenic axial compressor will also be in a cryogenic environment for a long time, and will frequently withstand temperature alternation during the temperature rise and fall stages. The operating environment is extremely harsh, the operating conditions are extremely complex, and the operating stability requirements are extremely high. Correspondingly, very high requirements are put forward for the safety protection of this large-size cryogenic axial compressor, while the existing safety protection technologies cannot meet them.

[0004] Affected by the cryogenic operating environment, the safety protection methods, scopes, contents and key points of large-size cryogenic axial compressors are significantly different from those of existing safety protection technologies, which are prominently manifested in aspects such as the deformation of the casing in the cryogenic temperature range and its influence on the operating state of the shafting and the operating safety of moving blades, the influence of low-temperature flow medium on the operating condition points of the compressor, the heat preservation and adiabatic protection methods under cryogenic conditions, etc. In particular, safety interlock measures must be taken under cryogenic conditions to ensure that the large-size cryogenic axial compressor can be in a continuous and stable operating state and prevent the deformation of the shafting from affecting the operating performance and safety. Summary of the Invention

[0005] The object of the present invention is to provide a safety interlock method for a large-size cryogenic axial flow compressor, so as to solve the problem of lack of safety protection technology for large-size cryogenic axial flow compressors in practical engineering applications in the prior art.

[0006] The present invention discloses a safety interlock method for a large-size cryogenic axial flow compressor, which adopts a deceleration shutdown for 90 s, an emergency braking for 15 s, an emergency shutdown and a free shutdown interlock shutdown mode. The 15 s emergency braking has the highest priority, but when an emergency shutdown occurs simultaneously, only the emergency shutdown mode can be used for shutdown.

[0007] By setting various shutdown modes, the interlock shutdown requirements of the cryogenic axial flow compressor under different safety conditions can be met.

[0008] Further, the 90 s deceleration shutdown means that the deceleration time of the cryogenic axial flow compressor from the highest speed to the lowest speed is 90 s, and the lowest speed is 10% of the highest speed. This deceleration slope is the preferred and commonly used interlock shutdown mode, and it is also the inherent slope of the deceleration interlock of the cryogenic axial flow compressor.

[0009] Further, the 15 s emergency braking means that the cryogenic axial flow compressor can decelerate to 0 within 15 s at any speed, and it is only used when it is urgent to quickly stop the compressor.

[0010] Further, the emergency shutdown means that the high-voltage power of the high-voltage inverter is disconnected, and the cryogenic axial flow compressor decelerates to 0 by means of coasting shutdown, and it is only used when a fault involving high-voltage electricity occurs in the high-voltage motor or the high-voltage inverter.

[0011] Further, the free shutdown means that the high-voltage power of the high-voltage inverter is not disconnected, only the output is locked, and the cryogenic axial flow compressor coasts to a stop to 0, and it is only used during the commissioning period of the high-voltage inverter.

[0012] Further, the operation guarantee gas source includes a seal gas source, a heat preservation gas source and an instrument gas source. Among them, dry air with a dew point temperature ≤ -63°C or dry nitrogen with a water content ≤ 3 ppm is used as the seal gas source. After heating this seal gas source, it is directly filled and supplied into the seal cavity of the cryogenic axial flow compressor to insulate and adiabatically protect the seal cavity, block the leakage of the cryogenic medium in the flow path of the cryogenic axial flow compressor into the cavity, and at the same time reduce the cold quantity exchange speed between the flow path and the cavity, ensuring that the internal temperature of the cavity is continuously above 0°C.

[0013] Among them, the seal gas source preferably uses dry air with a large capacity and stable gas supply capacity as the main gas source, and dry nitrogen as the emergency gas source. The automatic judgment and switching of the gas supply circuit are carried out according to the dry air pressure, and the continuous supply of the seal gas source during abnormal pressure can be realized. The switching carrier is an electric valve.

[0014] The specific implementation methods are as follows:

[0015] (1) When the dry air pressure > 0.8 MpaA, dry air is used for gas supply;

[0016] (2) When the dry air pressure ≤ 0.8 MpaA, open the electric valve in the dry nitrogen gas supply circuit and fill in dry nitrogen;

[0017] (3) When the dry nitrogen pressure ≥ 0.75 MpaA, close the electric valve in the dry air supply circuit.

[0018] Among them, to ensure the continuous gas supply of the sealing gas source, the electric valve in the dry air supply circuit must be closed only after the dry nitrogen has started to supply gas stably.

[0019] Furthermore, the operating guarantee gas source uses dry nitrogen with a water content ≤ 3 ppm or dry air with a dew point temperature ≤ -63 °C as the heat preservation gas source. After heating this heat preservation gas source, it is supplied in a circulating manner and filled into the heat preservation cavity of the compressor to provide heat preservation and adiabatic protection for the heat preservation cavity, block the leakage of the cryogenic medium in the flow path of the low-temperature axial flow compressor into the cavity, and at the same time balance the heat exchange between the cold quantity of the deep-cooled casing and the heat inside the cavity, so as to realize that the inside of the cavity is continuously in a temperature range above 0 °C, and ensure the normal operation and safety of the normal-temperature equipment and instruments inside the cavity.

[0020] Among them, dry nitrogen is preferably used as the main gas source for the heat preservation gas source, which is consistent with the working medium in the flow path of the low-temperature axial flow compressor. Dry air is used as the emergency gas source. According to the dry nitrogen pressure, the manual switching of the gas supply circuit is carried out, and the continuous gas supply of the heat preservation gas source during abnormal pressure can be realized. The switching carrier is a manual stop valve.

[0021] The specific implementation methods are as follows:

[0022] (1) When the dry nitrogen pressure > 0.5 MpaA, dry nitrogen is used for gas supply;

[0023] (2) When the dry nitrogen pressure ≤ 0.5 MpaA, open the manual stop valve in the pipeline between the dry nitrogen and dry air supply circuits and fill dry air into the heat preservation cavity;

[0024] (3) When the dry air pressure > 0.5 MpaA, close the inlet valve at the front end of the dry nitrogen gas supply;

[0025] (4) Officially switch to using dry air for gas supply.

[0026] Among them, to ensure the continuous gas supply of the heat preservation gas source, the inlet valve at the front end of the dry nitrogen gas supply must be closed only after the dry air has started to supply gas stably.

[0027] Furthermore, the operating guarantee gas source uses dry air with a dew point temperature ≤ -63°C or dry nitrogen with a water content ≤ 3 ppm as the instrument gas source, and supplies driving gas to the pressure control valves of the above-mentioned sealing gas source and heat preservation gas source.

[0028] Among them, the instrument gas source preferably uses dry air as the main gas source and dry nitrogen as the emergency gas source. The manual switching of the gas supply circuit is carried out according to the dry air pressure, which can realize the continuous gas supply of the instrument gas source in case of abnormal pressure, provide a stable and continuous power source for the pressure control of the sealing gas source and the heat preservation gas source, and the switching carrier is a manual stop valve. The specific implementation method is as follows:

[0029] (1) When the dry air pressure > 0.6 MpaA, dry air is used for gas supply;

[0030] (2) When the dry air pressure ≤ 0.6 MpaA, open the manual stop valve in the dry nitrogen gas supply circuit and fill in dry nitrogen;

[0031] (3) When the dry nitrogen pressure > 0.6 MpaA, close the manual stop valve in the dry air gas supply circuit;

[0032] (4) Officially switch to using dry air for gas supply.

[0033] Among them, to ensure the continuous gas supply of the instrument gas source, the manual stop valve in the dry air gas supply circuit must be closed only after the dry nitrogen has started to supply gas stably.

[0034] Furthermore, the radial clearance between the tip of the moving blade of the low-temperature axial-flow compressor and the inner casing wall surface is measured and fed back in real time online, and the operating state of the moving blade is monitored and protected.

[0035] By monitoring the state of the moving blade, it can effectively prevent the clearance value from becoming smaller due to the 77K cryogenic deformation and shrinkage of the casing or the increase in the load of the low-temperature axial-flow compressor, resulting in rubbing or even collision between the tip of the moving blade and the inner casing wall surface, causing serious consequences.

[0036] Furthermore, the moving blades of the compressor include the first-stage and second-stage moving blades. Along the circumferential direction of the two-stage moving blades, a plurality of measuring points are respectively arranged on the inner casing wall surface opposite to the tip of the moving blade, and the measuring points are distributed on the top of the inner casing wall surface, the left side along the air flow direction, and the right side along the air flow direction.

[0037] Furthermore, the interlocking steps of the moving blade are as follows:

[0038] (1) When one of the clearance measuring points between the tip of the moving blade and the inner casing wall surface ≤ 2 mm, the low-temperature axial-flow compressor decelerates from the current speed to 40 r / min. By reducing the load, part of the clearance value can be restored, and at the same time, the harm degree can be effectively reduced in case of rubbing or collision;

[0039] (2) One of the clearance measurement points between the tip of the moving blade and the inner casing wall surface ≤ 1 mm, and the inherent slope of the 90 s deceleration interlock is used to decelerate from the current speed to 0.

[0040] (3) Start at a low speed, and resume the low-temperature axial flow compressor to the operating state to prevent the shafting from deforming due to long-term stoppage, with the speed ≤ 10 r / min.

[0041] Furthermore, a redundant implementation method of first-level alarm and deceleration interlock and second-level interlock shutdown is adopted. When the first-level alarm is triggered, the low-temperature axial flow compressor adopts the inherent slope of the 90 s deceleration interlock and directly decelerates from the speed at the time of alarm trigger to 40 r / min or 100 r / min; when the second-level interlock shutdown is triggered, the low-temperature axial flow compressor shuts down by the 90 s deceleration shutdown method.

[0042] Furthermore, when the interlocks for decelerating to 40 r / min and 100 r / min occur simultaneously, the deceleration to 100 r / min has a higher priority.

[0043] Furthermore, the signals for the low-temperature axial flow compressor to decelerate to 40 r / min include one of the following: the temperature of one of the multiple measurement points of the bearing ≥ 90 °C, the vibration of one of the multiple measurement points of the front shaft and the rear shaft ≥ 50 μm, the vibration of one of the multiple measurement points of the thrust-bearing combined shaft ≥ 120 μm, the vibration of one of the multiple measurement points of the bearing housing ≥ 6.3 mm / s, the displacement of one of the two measurement points of the shaft displacement ≥ 0.95 mm or ≤ -0.95 mm, the shafting torque ≥ 1500 kN·m, the operating condition point touches one of the surge alarm line, the anti-surge line, and the actual surge line, the UPS mains power status is abnormal, the sealed gas source pressure ≤ 0.8 MpaA and the sealed cavity pressure ≤ 100 KPaA, the lubricating oil source pressure ≤ 0.25 MpaA, the circulating cooling water pressure ≤ 0.25 MpaA, and the communication between the low-temperature axial flow compressor and the total control system of the test bench where it is located is interrupted.

[0044] Furthermore, the signals for the low-temperature axial flow compressor to decelerate to 100 r / min include one of the following: the jacking oil source pressure of the compressor ≤ 9.5 MpaA, the jacking oil source pressure of the motor ≤ 5.5 MpaA. Only when the speed of the low-temperature axial flow compressor is 100 r / min or above, even if the jacking oil source pressure is abnormal and cannot be quickly restored, the shafting can still operate safely and stably.

[0045] Furthermore, when the low-temperature axial flow compressor decelerates to 40 r / min or 100 r / min, if the included parameters still exceed the interlock value, then a 90 s deceleration shutdown is triggered, and the signals for setting the interlock value include one of the following:

[0046] The temperature at one of multiple measuring points of the bearing ≥ 110°C, the vibration at one of multiple measuring points of the front shaft and the rear shaft ≥ 75 μm, the vibration at one of multiple measuring points of the thrust - support combined shaft ≥ 150 μm, the vibration at one of multiple measuring points of the bearing housing ≥ 11 mm / s, the displacement at one of the two measuring points of the shaft displacement ≥ 1.2 mm or ≤ -1.2 mm, the sealed air source pressure ≤ 0.5 MpaA and the sealed cavity pressure ≤ 95 KPaA, and the lubricating oil source pressure ≤ 0.12 MpaA.

[0047] Furthermore, stress and thermal expansion amount suffered by the casing of the low - temperature axial - flow compressor after cryogenic cooling are measured and fed back in real time, and stress and strain of the mechanical structure under cryogenic conditions are monitored and protected in real time. Multiple stress measuring points are arranged on the inner casing and the outer casing of the cryogenic axial - flow compressor respectively, and the alarm value is set at 230 MPa; multiple thermal expansion measuring points are arranged at the axial position of the outer casing, and the alarm value is set at 20 mm. When one of the stress or thermal expansion measuring points exceeds the alarm value, the compressor starts to run at an increased speed, generating heat to heat and warm up the air flow in the flow channel.

[0048] Furthermore, the lubricating oil source pressure adopts a three - level interlock strategy, and alarm values for the main - standby pump switching of the lubricating oil pump and the start - up of the emergency oil pump are set in segments. The specific implementation method is as follows:

[0049] (1) When the lubricating oil source pressure ≤ the alarm value of 0.25 MpaA for the main - standby pump switching of the lubricating oil pump, the standby oil pump is automatically put into operation to supply lubricating oil continuously, and the synchronous speed is reduced to 40 r / min;

[0050] (2) When the standby oil pump fails to be put into operation normally, or the lubricating oil source pressure continues to decrease to ≤ the alarm value of 0.12 MpaA for the start - up of the emergency oil pump after being put into operation, the emergency oil pump is automatically put into operation to supply lubricating oil continuously;

[0051] (3) When the operation instruction of the emergency oil pump is at a high level, the synchronous speed is reduced to 0 by decelerating and stopping in 90 s.

[0052] The power circuit and control circuit of the main - standby pumps of the lubricating oil pump adopt the same power supply, and the power circuit and control circuit of the emergency oil pump are connected to another power supply. The two power supplies are completely independent;

[0053] The interlock strategy is only effective during the operation of the low - temperature axial - flow compressor. The criterion for the compressor being in the operation period is that the speed ≥ 1.5 r / min.

[0054] Connecting the power circuit and control circuit of the emergency oil pump to another power supply can effectively ensure the continuous and stable supply of the lubricating oil source.

[0055] Furthermore, configure an uninterruptible power supply that covers the operation guarantee gas source, jacking oil source, lubricating oil source, and all-power equipment of the control system, with a continuous power supply time of ≥5 minutes. It can effectively ensure the continuous operation of the equipment after the mains power supply in the field area where the cryogenic axial compressor is located is abnormally cut off and before the emergency guarantee power supply is started.

[0056] Furthermore, the safety interlock objects include the shafting operation state, operating condition point position, moving blade operation state, casing strain stress state, UPS operation state, motor operation state, frequency converter operation state, operation guarantee gas source state, lubrication and jacking oil source state, circulating cooling water state, and cryogenic axial compressor test bench position state.

[0057] Furthermore, the shafting operation state includes bearing temperature, shaft vibration, bearing housing vibration, shaft displacement, and torque;

[0058] The operating condition point position includes touching the surge alarm line, touching the anti-surge line, and touching the actual surge line. The casing strain stress state includes casing stress and casing thermal expansion;

[0059] The UPS operation state includes mains power state, inverter state, bypass state, load state, and fan failure;

[0060] The motor operation state includes cooling fan overload, abnormal AC contactor, low insulation monitoring value, and water leakage switch;

[0061] The frequency converter operation state includes light faults and heavy faults;

[0062] The lubrication and jacking oil source state includes lubricating oil source pressure, oil tank temperature, compressor jacking oil source pressure, and motor jacking oil source pressure;

[0063] The circulating cooling water state includes cooling water pressure and cooling water temperature;

[0064] The cryogenic axial compressor test bench position state includes flow path pressure, flow path temperature, and other system states to which the test bench belongs.

[0065] Compared with the prior art, the beneficial effects of the present invention are:

[0066] 1. Reasonable and effective sealing cavities, thermal insulation cavities for thermal insulation and adiabatic protection measures, and interlock measures such as moving blades, casing stress, and thermal expansion are taken, expanding the temperature application range of the axial compressor safety operation protection technology from 158K to 77K;

[0067] 2. Considering the casing shrinkage deformation under cryogenic specific conditions and the impact of this deformation on the operation safety of moving blades, the safety interlock objects and scope are expanded;

[0068] 3. A safety interlock shutdown method under specific cryogenic conditions is proposed. Compared with the common method of immediately and emergently shutting down the unit when it is abnormal in the prior art, a speed reduction interlock is preferentially adopted to maintain the continuous operation state of the axial flow compressor, effectively preventing problems such as uneven heat absorption and shafting deformation caused by sudden shutdown under cryogenic conditions;

[0069] 4. The specific methods, implementation conditions and priorities of the safety interlock shutdown of the axial flow compressor are defined. Compared with the prior art where there is only one emergency shutdown method commonly used, the shutdown methods are more targeted, scientific and reasonable, which is beneficial to protecting the safety of the equipment and extending its service life;

[0070] 5. The UPS power supply hardware equipment is extended. Compared with the prior art where only the control power supply is connected to the emergency power supply of the UPS, all the equipment of the operation guarantee gas source, lubrication and jacking oil source are connected to the UPS, which can effectively guarantee the continuity of equipment operation during the power failure of the commercial power, and then maintain the continuous operation state of the axial flow compressor under cryogenic conditions;

[0071] 6. It is more targeted at the operating characteristics of the heavy-duty shafting of large axial flow compressors. Compared with the prior art, when the axial flow compressor abnormally reduces speed, the applicable speed range when the jacking oil source is abnormal and cannot be quickly restored is preferentially considered to ensure the effective establishment of the shafting oil film;

[0072] 7. A multi-level interlock strategy for the lubricating oil source is adopted, an interlock method applicable to different pressure ranges is proposed, and a redundant power supply circuit is configured to realize the continuous supply of the lubricating oil source, providing support for the continuous operation state of the compressor under cryogenic conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 is the principle flow chart of the present invention.

[0074] Figure 2 is the implementation flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0075] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments.

[0076] Example 1

[0077] A safety interlock method for a large-sized cryogenic axial flow compressor, and the safety interlock objects include the operating state of the shafting, the position of the operating condition point, the operating state of the moving blades, the strain and stress state of the casing, the operating state of the UPS, the operating state of the motor, the operating state of the frequency converter, the state of the operating guarantee air source, the state of the lubricating and jacking oil source, the state of the circulating cooling water, and the state of the cryogenic axial flow compressor test bench position.

[0078] Adopt a 90s decelerated shutdown, a 15s emergency brake, an emergency shutdown, and a free shutdown interlock shutdown method. The 15s emergency brake has the highest priority. However, when an emergency shutdown occurs concurrently, only the emergency shutdown method can be used for shutdown.

[0079] The 90s decelerated shutdown means that the deceleration time of the cryogenic axial flow compressor from the highest speed to the lowest speed is 90s, and the lowest speed is 10% of the highest speed. This deceleration slope is the preferred and commonly used interlock shutdown method, and it is also the inherent slope of the deceleration interlock of the cryogenic axial flow compressor.

[0080] The 15s emergency brake means that the cryogenic axial flow compressor can decelerate to 0 within 15s at any speed, and it is only used when it is urgent to quickly stop the compressor.

[0081] The emergency shutdown means that the high-voltage of the high-voltage frequency converter is disconnected, and the cryogenic axial flow compressor decelerates to 0 by means of coasting shutdown. It is only used when a fault involving high-voltage electricity occurs in the high-voltage motor or high-voltage frequency converter.

[0082] The free shutdown means that the high-voltage of the high-voltage frequency converter is not disconnected, only the output is blocked, and the cryogenic axial flow compressor coasts to 0. It is only used during the debugging period of the high-voltage frequency converter.

[0083] The operating guarantee air source includes a seal air source, a heat preservation air source, and an instrument air source. Among them, dry air with a dew point temperature ≤ -63°C or dry nitrogen with a water content ≤ 3ppm is used as the seal air source. After heating this seal air source, it is directly filled and supplied into the seal cavity of the cryogenic axial flow compressor to insulate and adiabatically protect the seal cavity, block the leakage of the cryogenic medium in the flow path of the cryogenic axial flow compressor into the cavity, and at the same time reduce the cold quantity exchange speed between the flow path and the cavity, ensuring that the inside of the cavity continuously remains in a temperature range above 0°C.

[0084] Among them, the seal air source preferably uses dry air with a large capacity and stable air supply capacity as the main air source, and dry nitrogen as the emergency air source. The automatic judgment and switching of the air supply circuit are carried out according to the dry air pressure, and continuous air supply of the seal air source can be realized when the pressure is abnormal. The switching carrier is an electric valve.

[0085] The specific implementation method is as follows:

[0086] (1) When the dry air pressure > 0.8MpaA, dry air is used for air supply;

[0087] (2) The dry air pressure ≤ 0.8 MpaA. Open the electric valve located in the dry nitrogen supply circuit and fill in dry nitrogen.

[0088] (3) The dry nitrogen pressure ≥ 0.75 MpaA. Close the electric valve located in the dry air supply circuit.

[0089] Among them, to ensure the continuous supply of the sealed gas source, the electric valve in the dry air supply circuit must be closed only after the dry nitrogen has started to be stably supplied.

[0090] The operation guarantee gas source uses dry nitrogen with a water content ≤ 3 ppm or dry air with a dew point temperature ≤ -63°C as the heat preservation gas source. After heating this heat preservation gas source, it is supplied in a circulating manner to the heat preservation cavity of the compressor to insulate and adiabatically protect the heat preservation cavity, block the leakage of the cryogenic medium in the flow path of the low-temperature axial flow compressor to the cavity, and at the same time balance the heat exchange between the cold quantity of the casing after being cryogenically cooled and the inside of the cavity, so as to keep the inside of the cavity continuously in a temperature range above 0°C and ensure the normal operation and safety of the normal-temperature equipment and instruments inside the cavity.

[0091] Among them, the heat preservation gas source preferably selects dry nitrogen as the main gas source, which is consistent with the working medium in the flow path of the low-temperature axial flow compressor. Dry air is used as the emergency gas source. According to the dry nitrogen pressure, manual switching of the supply circuit is carried out, and continuous supply of the heat preservation gas source during abnormal pressure can be realized. The switching carrier is a manual stop valve.

[0092] The specific implementation method is as follows:

[0093] (1) The dry nitrogen pressure > 0.5 MpaA. Supply gas using dry nitrogen.

[0094] (2) The dry nitrogen pressure ≤ 0.5 MpaA. Open the manual stop valve on the pipeline between the dry nitrogen and dry air supply circuits and fill dry air into the heat preservation cavity.

[0095] (3) The dry air pressure > 0.5 MpaA. Close the intake valve at the front end of the dry nitrogen supply.

[0096] (4) Officially switch to supply gas using dry air.

[0097] Among them, to ensure the continuous supply of the heat preservation gas source, the intake valve at the front end of the dry nitrogen supply must be closed only after the dry air has started to be stably supplied.

[0098] The operation guarantee gas source uses dry air with a dew point temperature ≤ -63°C or dry nitrogen with a water content ≤ 3 ppm as the instrument gas source to provide driving gas for the pressure control valves of the above-mentioned sealed gas source and heat preservation gas source.

[0099] Among them, the instrument air source preferably uses dry air as the main air source and dry nitrogen as the emergency air source. The manual switching of the air supply circuit is carried out according to the dry air pressure, which can realize the continuous supply of the instrument air source in case of abnormal pressure, provide a stable and continuous power source for the pressure control of the seal air source and the heat preservation air source, and the switching carrier is a manual stop valve. The specific implementation method is as follows:

[0100] (1) When the dry air pressure > 0.6 MpaA, dry air is used for air supply;

[0101] (2) When the dry air pressure ≤ 0.6 MpaA, open the manual stop valve located in the dry nitrogen air supply circuit and fill in dry nitrogen;

[0102] (3) When the dry nitrogen pressure > 0.6 MpaA, close the manual stop valve located in the dry air air supply circuit;

[0103] (4) Officially switch to using dry air for air supply.

[0104] Among them, to ensure the continuous supply of the instrument air source, the manual stop valve of the dry air air supply circuit must be closed only after the dry nitrogen has started to supply air stably.

[0105] The radial clearance between the tip of the moving blade of the low-temperature axial-flow compressor and the inner casing wall surface is measured and fed back in real time online to monitor the operating state of the moving blade and implement operation protection. The moving blades of the compressor include the first-stage and second-stage moving blades. Along the circumferential direction of the two-stage moving blades, a plurality of measuring points are respectively arranged on the inner casing wall surface opposite to the tip of the moving blade, and the measuring points are distributed on the top of the inner casing wall surface, the left side along the air flow direction and the right side along the air flow direction.

[0106] The interlock steps of the moving blade are as follows:

[0107] (1) When one of the clearance measuring points between the tip of the moving blade and the inner casing wall surface ≤ 2 mm, the low-temperature axial-flow compressor reduces its speed from the current speed to 40 r / min. By reducing the load, some clearance values can be restored, and at the same time, the degree of harm can be effectively reduced in case of rubbing or collision;

[0108] (2) When one of the clearance measuring points between the tip of the moving blade and the inner casing wall surface ≤ 1 mm, the speed is reduced from the current speed to 0 at the inherent slope of the 90 s speed reduction interlock;

[0109] (3) Start at a low speed and restore the low-temperature axial-flow compressor to the operating state to prevent the shafting from deforming due to long-term stop, and the speed ≤ 10 r / min.

[0110] Adopt a redundant implementation method of first-level alarm and speed reduction interlock, and second-level interlock shutdown. When the first-level alarm is triggered, the low-temperature axial-flow compressor adopts an inherent slope of speed reduction interlock for 90s, and directly reduces the speed from the speed at the time of alarm trigger to 40r / min or 100r / min; when the second-level interlock shutdown is triggered, the low-temperature axial-flow compressor shuts down by adopting a 90s deceleration shutdown method. When the interlocks of reducing the speed to 40r / min or 100r / min occur simultaneously, the priority of reducing the speed to 100r / min is higher.

[0111] The signals for the low-temperature axial-flow compressor to reduce the speed to 40r / min include one of the following: the temperature of one of the multiple measuring points of the bearing ≥ 90°C, the vibration of one of the multiple measuring points of the front shaft and the rear shaft ≥ 50μm, the vibration of one of the multiple measuring points of the thrust-bearing combined shaft ≥ 120μm, the vibration of one of the multiple measuring points of the bearing housing ≥ 6.3mm / s, the displacement of one of the two measuring points of the shaft displacement ≥ 0.95mm or ≤ -0.95mm, the shaft system torque ≥ 1500kN·m, the operating condition point touches one of the surge alarm line, anti-surge line, and actual surge line, the UPS mains power status is abnormal, the seal gas source pressure ≤ 0.8MpaA and the seal cavity pressure ≤ 100KPaA, the lubricating oil source pressure ≤ 0.25MpaA, the circulating cooling water pressure ≤ 0.25MpaA, and the communication between the low-temperature axial-flow compressor and the total control system of the test bench where it is located is interrupted.

[0112] The signals for the low-temperature axial-flow compressor to reduce the speed to 100r / min include one of the following: the jacking oil source pressure of the compressor ≤ 9.5MpaA, the jacking oil source pressure of the motor ≤ 5.5MpaA. Only when the speed of the low-temperature axial-flow compressor is 100r / min and above, even if the jacking oil source pressure is abnormal and cannot be quickly restored, the shaft system can still operate safely and stably.

[0113] After the low-temperature axial-flow compressor reduces the speed to 40r / min or 100r / min, if the included parameters still exceed the interlock value, a 90s deceleration shutdown is triggered. The signals for setting the interlock value include one of the following:

[0114] The temperature of one of the multiple measuring points of the bearing ≥ 110°C, the vibration of one of the multiple measuring points of the front shaft and the rear shaft ≥ 75μm, the vibration of one of the multiple measuring points of the thrust-bearing combined shaft ≥ 150μm, the vibration of one of the multiple measuring points of the bearing housing ≥ 11mm / s, the displacement of one of the two measuring points of the shaft displacement ≥ 1.2mm or ≤ -1.2mm, the seal gas source pressure ≤ 0.5MpaA and the seal cavity pressure ≤ 95KPaA, the lubricating oil source pressure ≤ 0.12MpaA.

[0115] Measure and feedback the stress and thermal expansion of the low-temperature axial compressor casing in real time after cryogenic cooling, monitor and protect the stress and strain of the mechanical structure under deep low-temperature conditions. Arrange multiple stress measurement points on the inner and outer casings of the deep low-temperature axial compressor respectively, and set the alarm value at 230 MPa; arrange multiple thermal expansion measurement points at the axial position of the outer casing, and set the alarm value at 20 mm. When one of the stress or thermal expansion measurement points exceeds the alarm value, the compressor starts to run at an increased speed, generating heat to heat the airflow in the flow path for temperature recovery.

[0116] The lubricating oil source pressure adopts a three-stage interlock strategy, and two-stage alarm values for the main and standby pump switching of the lubricating oil pump and the start of the emergency oil pump are set in sections. The specific implementation method is as follows:

[0117] (1) When the lubricating oil source pressure ≤ the alarm value of 0.25 MpaA for the main and standby pump switching of the lubricating oil pump, the standby oil pump is automatically put into operation, continuously supplying lubricating oil, and the synchronous speed is reduced to 40 r / min;

[0118] (2) If the standby oil pump fails to be put into operation normally, or the lubricating oil source pressure continues to drop to ≤ the alarm value of 0.12 MpaA for the start of the emergency oil pump after being put into operation, the emergency oil pump is automatically put into operation, continuously supplying lubricating oil;

[0119] (3) When the operation instruction of the emergency oil pump is at a high level, the synchronous speed is reduced to 0 by decelerating and stopping within 90 s.

[0120] The power circuit and control circuit of the main and standby pumps of the lubricating oil pump adopt the same power supply, and the power circuit and control circuit of the emergency oil pump are connected to another power supply. The two power supplies are completely independent;

[0121] The interlock strategy is only effective during the operation of the low-temperature axial compressor. The criterion for the compressor to be in the operation period is that the speed ≥ 1.5 r / min.

[0122] Connecting the power circuit and control circuit of the emergency oil pump to another power supply can effectively ensure the continuous and stable supply of the lubricating oil source.

[0123] Configure an uninterruptible power supply covering the operating guarantee gas source, jacking oil source, lubricating oil source, and all-power equipment of the control system, with a continuous power supply time ≥ 5 minutes, which can effectively ensure the continuous operation of the equipment after the municipal power supply in the field area where the low-temperature axial compressor is located is abnormally cut off and before the emergency guarantee power supply is started.

[0124] The operating state of the shafting includes bearing temperature, shaft vibration, bearing housing vibration, shaft displacement, and torque;

[0125] The positions of the operating condition points include touching the surge alarm line, touching the anti-surge line, and touching the actual surge line. The stress and strain state of the casing includes casing stress and casing thermal expansion;

[0126] The UPS operating status includes mains power status, inverter status, bypass status, load status, and fan failure;

[0127] The motor operating status includes cooling fan overload, abnormal AC contactor, low insulation monitoring value, and water leakage switch;

[0128] The frequency converter operating status includes minor faults and major faults;

[0129] The lubrication and jacking oil source status includes lubricating oil source pressure, oil tank temperature, compressor jacking oil source pressure, and motor jacking oil source pressure;

[0130] The circulating cooling water status includes cooling water pressure and cooling water temperature. The deep low-temperature axial flow compressor test bench position status includes flow channel pressure, flow channel temperature, and other system statuses belonging to this test bench position.

[0131] The above are the implementation manners listed in this embodiment. However, this embodiment is not limited to the above optional implementation manners. Those skilled in the art can obtain many other implementation manners by arbitrarily combining the above manners. Anyone can obtain various other forms of implementation manners under the inspiration of this embodiment. The above specific implementation manners should not be construed as limiting the protection scope of this embodiment. The protection scope of this embodiment should be defined by the claims, and the description can be used to interpret the claims.

Claims

1. A safety interlocking method for a large-size cryogenic axial compressor, characterized in that: The machine adopts the 90s deceleration stop, 15s emergency brake, emergency stop and free stop interlocking stop mode. The 15s emergency brake has the highest priority. However, when emergency stops occur simultaneously, only the emergency stop mode can be used for shutdown. The 90s deceleration shutdown means that the deceleration time from the maximum speed to the minimum speed of the low-temperature axial flow compressor is 90s, and the minimum speed is 10% of the maximum speed. This deceleration slope is the preferred and commonly used interlocking shutdown mode, and is also the inherent slope of the low-temperature axial flow compressor deceleration interlock; The 15s emergency brake means that the low-temperature axial flow compressor can be decelerated to 0 within 15s at any speed, and is only used when the compressor needs to be shut down quickly; The emergency shutdown means that the high voltage of the high voltage inverter is disconnected and the low temperature axial compressor is decelerated to 0 by idling shutdown. It is only used when the high voltage motor or high voltage inverter has a fault involving high voltage. The free shutdown means that the high voltage power of the high voltage inverter is not disconnected, only the output is locked, and the low temperature axial flow compressor coasts to stop at 0. It is only used during the debugging of the high voltage inverter.

2. A safety interlocking method for a large-size cryogenic axial compressor according to claim 1, characterized in that: The operation guarantee gas source includes sealing gas source, insulation gas source and instrument gas source.

3. A safety interlocking method for a large-size cryogenic axial compressor according to claim 2, characterized in that: Use dry air with a dew point temperature of ≤-63°C or dry nitrogen with a water content of ≤3ppm as the sealing gas source; Use dry nitrogen with a water content of ≤3ppm or dry air with a dew point temperature of ≤-63℃ as the insulation gas source; Use dry air with a dew point temperature ≤-63°C or dry nitrogen with a water content ≤3ppm as the instrument air source.

4. A safety interlocking method for a large-size cryogenic axial compressor according to claim 1, characterized in that: Real-time online measurement and feedback of the radial clearance between the top of the low-temperature axial compressor moving blade and the inner casing wall, to monitor and protect the running status of the moving blades when the casing is deformed due to deep low temperature or the load increases.

5. A safety interlocking method for a large-size cryogenic axial compressor according to claim 1, characterized in that: A redundant implementation method of first-level alarm and speed reduction interlock and second-level interlock shutdown is adopted. When the first-level alarm is triggered, the low-temperature axial flow compressor adopts the 90s speed reduction interlock inherent slope to directly reduce the speed from the speed when the alarm is triggered to 40r / min or 100r / min; when the second-level interlock shutdown is triggered, the low-temperature axial flow compressor stops by 90s deceleration shutdown.

6. A safety interlocking method for a large-size cryogenic axial compressor according to claim 1, characterized in that: It is equipped with an uninterruptible power supply that covers the operation guarantee gas source, jacking oil source, lubricating oil source and full-power equipment of the control system. The continuous power supply time is ≥ 5 minutes. It can effectively ensure the continuous operation of the equipment after an abnormal power outage in the area where the low-temperature axial flow compressor is located and before the emergency guarantee power supply is started.

7. A safety interlocking method for a large-size cryogenic axial compressor according to claim 1, characterized in that: The casing strain stress state is measured and fed back in real time online, wherein the casing strain stress state includes casing stress and casing thermal expansion.

Images