阅读说明：本技术 干气耦合迷宫密封的超临界二氧化碳涡轮轴端密封方法及装置 (Supercritical carbon dioxide turbine shaft end sealing method and device adopting dry gas coupling labyrinth sealing ) 是由 刘光旭 黄彦平 王俊峰 于 2020-04-29 设计创作，主要内容包括：本发明公开了干气耦合迷宫密封的超临界二氧化碳涡轮轴端密封方法及装置,方法采用干气密封实现压气机和透平的轴端密封,采用迷宫密封减少干气密封失效时的二氧化碳泄漏量。所述轴端密封装置包括干气密封单元和迷宫密封单元,所述干气密封单元能够实现压气机和透平的轴端密封,所述迷宫密封单元能够减少干气密封失效时的二氧化碳泄漏量。密封方法包括对干气密封的进气温度和流量进行协调控制的步骤以及启动压气机和透平后对干气密封泄漏进行监视控制的步骤。本发明利用干气密封实现了大功率高转速超临界二氧化碳压气机和透平轴端高效密封,利用迷宫密封减缓干气密封失效时压气机和透平泄漏量,确保压气机和透平安全停机,显著增加了机组安全性。(The invention discloses a method and a device for sealing the shaft end of a supercritical carbon dioxide turbine by dry gas coupling labyrinth seal. The shaft end sealing device comprises a dry gas sealing unit and a labyrinth sealing unit, the dry gas sealing unit can realize shaft end sealing of the gas compressor and the turbine, and the labyrinth sealing unit can reduce the carbon dioxide leakage amount when the dry gas sealing fails. The sealing method comprises the steps of performing coordinated control on the inlet temperature and the flow of the dry gas seal and monitoring and controlling the leakage of the dry gas seal after the compressor and the turbine are started. The invention realizes the high-efficiency sealing of the shaft ends of the high-power high-rotating-speed supercritical carbon dioxide gas compressor and the turbine by using the dry gas seal, reduces the leakage amount of the gas compressor and the turbine when the dry gas seal fails by using the labyrinth seal, ensures the safe shutdown of the gas compressor and the turbine, and obviously increases the safety of the unit.)

1. A shaft end sealing method of a supercritical carbon dioxide turbine with dry gas coupling labyrinth seal is characterized in that shaft end sealing of a gas compressor and a turbine is achieved through dry gas seal, leakage of carbon dioxide is reduced when the dry gas seal fails through the labyrinth seal, and safe shutdown of the gas compressor and the turbine is guaranteed.

2. The method for sealing the supercritical carbon dioxide turbine shaft end of the dry gas coupling labyrinth seal according to claim 1, characterized in that the method comprises the steps of coordinately controlling the inlet temperature and the flow rate of the dry gas seal and monitoring and controlling the leakage of the dry gas seal after the compressor and the turbine are started.

3. The shaft end sealing method of the dry gas coupling labyrinth sealed supercritical carbon dioxide turbine is characterized in that in the step of coordinately controlling the inlet temperature and the flow rate of the dry gas seal, the lowest inlet temperature of the dry gas seal is calculated based on the equal specific enthalpy expansion, and the inlet temperature and the flow rate of the dry gas seal are automatically controlled; in the step of monitoring and controlling the leakage of the dry gas seal, the working states of the compressor and the turbine are controlled in time by monitoring the leakage amount of the dry gas seal.

4. The utility model provides a dry gas coupling labyrinth seal's super supercritical carbon dioxide turbine shaft end sealing device which characterized in that, shaft end sealing device includes dry gas seal unit and labyrinth seal unit, dry gas seal unit can realize the shaft end seal of compressor and turbine, labyrinth seal unit can reduce the carbon dioxide leakage volume when dry gas seal became invalid, ensures compressor and turbine safety shut down.

5. The dry gas coupling labyrinth sealed supercritical carbon dioxide turbine shaft end sealing device as claimed in claim 4, wherein the dry gas sealing unit comprises a dry gas sealing dynamic ring and a dry gas sealing static ring which are arranged between the compressor/turbine rotor and the compressor/turbine cylinder and are matched with each other, wherein a dry gas sealing film can be formed between the dry gas sealing dynamic ring and the dry gas sealing static ring.

6. The dry gas coupling labyrinth sealed supercritical carbon dioxide turbine shaft end sealing device as claimed in claim 5, characterized in that the dry gas sealing static ring is arranged on the inner wall of the compressor/turbine cylinder, the dry gas sealing dynamic ring is arranged on the compressor/turbine rotor, and the dry gas sealing static ring is connected with the end wall of the compressor/turbine cylinder through an elastic element.

7. The dry gas coupled labyrinth sealed supercritical carbon dioxide turbine shaft end sealing device according to claim 4, wherein the labyrinth seal unit comprises a first labyrinth seal body and a second labyrinth seal body disposed between the compressor/turbine rotor and the compressor/turbine cylinder, the first labyrinth seal body disposed on the low pressure side and the second labyrinth seal body disposed on the high pressure side.

8. The dry gas coupled labyrinth sealed supercritical carbon dioxide turbine shaft end seal device of claim 4, further comprising a dry gas seal monitoring unit comprising an inlet monitoring subunit and an outlet monitoring subunit in communication with the compressor/turbine cylinder, the inlet monitoring subunit comprising a heater, a control valve, a pressure sensor, a first flow meter and a temperature sensor, the outlet monitoring subunit comprising a second flow meter.

9. The method for sealing the supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupling labyrinth seal according to any one of claims 4 to 8, characterized in that the sealing method comprises the steps of coordinately controlling the inlet temperature and the flow rate of the dry gas seal and monitoring and controlling the leakage of the dry gas seal after the compressor and the turbine are started.

10. The sealing method of the shaft end sealing device of the supercritical carbon dioxide turbine with the dry gas coupling labyrinth seal according to claim 9, characterized in that in the step of coordinately controlling the inlet temperature and the flow rate of the dry gas seal, the lowest inlet temperature of the dry gas seal is calculated based on the isenthalpic expansion and the inlet temperature and the flow rate of the dry gas seal are automatically controlled; in the step of monitoring and controlling the dry gas seal leakage after the compressor and the turbine are started, the compressor/turbine rotor is lifted to a target rotating speed, then the dry gas seal leakage flow is monitored, and the working states of the compressor and the turbine are controlled in time.

Technical Field

The invention relates to the technical field of advanced turbine equipment, in particular to a method and a device for sealing a shaft end of a supercritical carbon dioxide turbine by using dry gas coupling labyrinth seal.

Background

The supercritical carbon dioxide power conversion system is an innovative power conversion technical concept, and a compressor and a turbine are core equipment of the system.

The compressor and the turbine belong to high-rotation-speed turbine equipment, and compared with the traditional air working medium, the supercritical carbon dioxide compressor and the turbine need to solve the problem of sealing of the supercritical carbon dioxide at high rotation speed and high pressure, and the safety and the economical efficiency of a system are directly influenced by the quality of the sealing effect.

The traditional labyrinth seal, mechanical seal and the like have the problems of large leakage amount, incapability of realizing high-rotating-speed operation and the like, are not suitable for high-power high-rotating-speed supercritical carbon dioxide compressors and turbines, have good dry gas seal effect, but have poor long-term operation reliability compared with the traditional seal. There is no effective supercritical carbon dioxide compressor and turbine shaft end sealing method disclosed.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method and a device for sealing the shaft end of a supercritical carbon dioxide turbine by dry gas coupling labyrinth seal, which can realize the high-efficiency sealing of the shaft ends of a high-power high-rotating-speed supercritical carbon dioxide compressor and the turbine.

The invention provides a method for sealing the shaft end of a supercritical carbon dioxide turbine by dry gas coupling labyrinth seal, which adopts dry gas seal to realize the shaft end seal of a gas compressor and the turbine, adopts labyrinth seal to reduce the leakage amount of carbon dioxide when the dry gas seal fails, and ensures the safe shutdown of the gas compressor and the turbine.

According to one embodiment of the method for sealing the shaft end of the supercritical carbon dioxide turbine with the dry gas coupling labyrinth seal, the method comprises the steps of performing coordinated control on the inlet temperature and the flow rate of the dry gas seal and performing monitoring control on the leakage of the dry gas seal after the compressor and the turbine are started.

According to one embodiment of the shaft end sealing method of the supercritical carbon dioxide turbine with the dry gas coupling labyrinth seal, in the step of coordinately controlling the inlet temperature and the flow of the dry gas seal, the lowest inlet temperature of the dry gas seal is calculated based on the equal specific enthalpy expansion, and the inlet temperature and the flow of the dry gas seal are automatically controlled; in the step of monitoring and controlling the leakage of the dry gas seal, the working states of the compressor and the turbine are controlled in time by monitoring the leakage amount of the dry gas seal.

The invention also provides a supercritical carbon dioxide turbine shaft end sealing device with dry gas coupling labyrinth seal, which comprises a dry gas sealing unit and a labyrinth sealing unit, wherein the dry gas sealing unit can realize shaft end sealing of a gas compressor and a turbine, and the labyrinth sealing unit can reduce the leakage amount of carbon dioxide when the dry gas sealing fails, so that the gas compressor and the turbine can be safely shut down.

According to one embodiment of the supercritical carbon dioxide turbine shaft end sealing device with the dry gas coupling labyrinth seal, the dry gas sealing unit comprises a dry gas sealing movable ring and a dry gas sealing static ring which are arranged between the compressor/turbine rotor and the compressor/turbine cylinder and matched with each other, wherein a dry gas sealing film can be formed between the dry gas sealing movable ring and the dry gas sealing static ring.

According to one embodiment of the supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupling labyrinth seal, the dry gas seal static ring is arranged on the inner wall of the compressor/turbine cylinder, the dry gas seal dynamic ring is arranged on the compressor/turbine rotor, and the dry gas seal static ring is connected with the end wall of the compressor/turbine cylinder through the elastic element.

According to one embodiment of the supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupled labyrinth seal of the present invention, the labyrinth seal unit includes a first labyrinth seal body and a second labyrinth seal body disposed between the compressor/turbine rotor and the compressor/turbine cylinder, the first labyrinth seal body being disposed on the low pressure side and the second labyrinth seal body being disposed on the high pressure side.

According to an embodiment of the supercritical carbon dioxide turbine shaft end sealing device with the dry gas coupling labyrinth seal, the shaft end sealing device further comprises a dry gas seal monitoring unit, the dry gas seal monitoring unit comprises an inlet monitoring subunit and an outlet monitoring subunit, the inlet monitoring subunit is communicated with the compressor/turbine cylinder and comprises a heater, a control valve, a pressure sensor, a first flowmeter and a temperature sensor, and the outlet monitoring subunit comprises a second flowmeter.

The invention further provides a sealing method of the supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupling labyrinth seal, which comprises the steps of coordinately controlling the inlet temperature and the flow rate of the dry gas seal and monitoring and controlling the dry gas seal leakage after the compressor and the turbine are started.

According to one embodiment of the sealing method of the supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupling labyrinth seal, in the step of coordinately controlling the inlet temperature and the flow of the dry gas seal, the lowest inlet temperature of the dry gas seal is calculated based on the equal specific enthalpy expansion, and the inlet temperature and the flow of the dry gas seal are automatically controlled; in the step of monitoring and controlling the dry gas seal leakage after the compressor and the turbine are started, the compressor/turbine rotor is lifted to a target rotating speed, then the dry gas seal leakage flow is monitored, and the working states of the compressor and the turbine are controlled in time.

Compared with the conventional scheme, the invention provides the method and the device for sealing the shaft end of the supercritical carbon dioxide turbine by using dry gas coupling labyrinth seal, the high-efficiency sealing of the shaft ends of the high-power high-rotating-speed supercritical carbon dioxide compressor and the turbine is realized by using the dry gas seal, the leakage amount of the compressor and the turbine is reduced by using the labyrinth seal when the dry gas seal fails, and the safety of a unit is obviously improved.

Drawings

Fig. 1 shows a schematic structural diagram of a supercritical carbon dioxide turbine shaft end sealing device of a dry gas coupling labyrinth seal according to an exemplary embodiment of the present invention.

Description of reference numerals:

the system comprises a compressor/turbine rotor 1, a dry gas seal dynamic ring 2, a dry gas seal static ring 3, a compressor/turbine cylinder 4, a first labyrinth seal body 5, a second labyrinth seal body 6, a heater 7, a control valve 8, a pressure sensor 9, a first flowmeter 10, a temperature sensor 11 and a second flowmeter 12.

Detailed Description

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

The invention provides a supercritical carbon dioxide compressor and turbine shaft end sealing method based on the coupling effect of dry gas seal and labyrinth seal, which adopts dry gas seal to realize shaft end sealing of the compressor and the turbine and adopts labyrinth seal to reduce the leakage amount of carbon dioxide when the dry gas seal fails. That is, the dry gas seal is used as the main seal, and the labyrinth seal is used as the standby seal after the dry gas seal fails, so that the outward carbon dioxide leakage rate of the compressor and the turbine is effectively reduced, and the safe shutdown of the compressor and the turbine is ensured.

Specifically, the method comprises the step of coordinately controlling the inlet temperature and the flow rate of the dry gas seal and the step of monitoring and controlling the leakage of the dry gas seal after the compressor and the turbine are started, wherein in the step of coordinately controlling the inlet temperature and the flow rate of the dry gas seal, the lowest inlet temperature of the dry gas seal is calculated based on equal-ratio enthalpy expansion, and the inlet temperature and the flow rate of the dry gas seal are automatically controlled, so that the inlet temperature of the dry gas seal is controlled within a preset range, and the phenomenon of carbon dioxide solidification in the dry gas seal is ensured to be avoided. And in the step of monitoring and controlling the leakage of the dry gas seal, the working states of the compressor and the turbine are controlled in time by monitoring the leakage amount of the dry gas seal.

The supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupling labyrinth seal of the present invention is specifically described below.

Fig. 1 shows a schematic structural diagram of a supercritical carbon dioxide turbine shaft end sealing device of a dry gas coupling labyrinth seal according to an exemplary embodiment of the present invention.

According to an exemplary embodiment of the invention, as shown in fig. 1, the supercritical carbon dioxide turbine shaft end sealing device of the dry gas coupling labyrinth seal comprises a dry gas sealing unit and a labyrinth sealing unit, wherein the dry gas sealing unit can realize shaft end sealing of a compressor and a turbine, and the labyrinth sealing unit can reduce the leakage amount of carbon dioxide when the dry gas sealing fails, so that the compressor and the turbine can be safely shut down.

Specifically, the dry gas sealing unit comprises a dry gas sealing movable ring 2 and a dry gas sealing static ring 3 which are arranged between a compressor/turbine rotor 1 and a compressor/turbine cylinder 4 and are matched with each other, wherein under normal conditions, dry gas sealing inlet air flowing in through a first flowmeter and a pipeline thereof is divided into two paths in front of an inlet of the dry gas sealing movable ring 2, one path of dry gas sealing inlet air flows through a second labyrinth seal 6 and enters the compressor/turbine, the other path of dry gas sealing inlet air flows between the dry gas sealing movable ring 2 and the dry gas sealing static ring 3, and a rigid gas film is formed between the dry gas sealing movable ring 2 and the dry gas sealing static ring 3 to prevent carbon dioxide from further leaking outwards.

The dry gas sealing static ring 3 is arranged on the inner wall of the compressor/turbine cylinder 4, the dry gas sealing moving ring 2 is arranged on the compressor/turbine rotor 1, and the dry gas sealing static ring 3 is connected with the end wall of the compressor/turbine cylinder 4 through an elastic element such as a spring.

The labyrinth seal unit according to the invention comprises a first labyrinth seal body 5 and a second labyrinth seal body 6 arranged between the compressor/turbine rotor 1 and the compressor/turbine cylinder 4, the first labyrinth seal body 5 being arranged on the low-pressure side and the second labyrinth seal body 6 being arranged on the high-pressure side. When the dry gas seal fails or the dry gas seal fails to admit air, high-pressure carbon dioxide in the compressor/turbine cylinder leaks outwards through the first labyrinth seal body 5 and the second labyrinth seal body 6, and the labyrinth seal unit serves as a spare seal at the moment, so that the outward leakage amount of the carbon dioxide of the compressor and the turbine is reduced.

If the dry gas seal inlet air temperature is too low, the pressure of carbon dioxide is gradually reduced when the carbon dioxide leaks outwards through the gap between the dry gas seal moving ring 2 and the dry gas seal static ring 3, the temperature of the carbon dioxide is reduced along with the pressure, and carbon dioxide solid particles are possibly formed in the gap between the dry gas seal moving ring 2 and the dry gas seal static ring 3, so that the dry gas seal moving ring 2 is damaged. In order to realize control and ensure safe and stable operation of dry gas seal, the shaft end sealing device also comprises a dry gas seal monitoring unit, wherein the dry gas seal monitoring unit comprises an inlet monitoring subunit and an outlet monitoring subunit which are communicated with the compressor/turbine cylinder 4, the inlet monitoring subunit is used for adjusting and controlling the inlet temperature and flow of the dry gas seal, and the outlet monitoring subunit is used for monitoring the outward carbon dioxide leakage amount.

Specifically, the inlet monitoring sub-unit includes a heater 7, a control valve 8, a pressure sensor 9, a first flow meter 10, and a temperature sensor 10, and piping connecting the respective components, and the outlet monitoring sub-unit includes a second flow meter 12. When the supercritical carbon dioxide turbine shaft end sealing device adopting the dry gas coupling labyrinth seal is adopted, the adopted sealing method comprises the steps of performing coordination control on the inlet temperature and the flow of the dry gas seal and monitoring and controlling the dry gas seal leakage after the compressor and the turbine are started. In the step of coordinately controlling the inlet temperature and the flow of the dry gas seal, the lowest inlet temperature of the dry gas seal is calculated based on the equal specific enthalpy expansion, and the inlet temperature and the flow of the dry gas seal are automatically controlled, so that the gap between the dry gas seal movable ring 2 and the dry gas seal static ring 3 is ensured not to form carbon dioxide solid particles; in the step of monitoring and controlling the dry gas seal leakage after the compressor and the turbine are started, the compressor/turbine rotor is lifted to a target rotating speed, then the dry gas seal leakage flow is monitored, and the working states of the compressor and the turbine are controlled in time.

The present invention is further illustrated by the following specific examples.

The structure of this embodiment employs a sealing device as shown in fig. 1.

Step 1: the method comprises the following steps of (1) coordinating and automatically controlling the temperature and the flow of dry gas seal inlet air, and specifically comprising the following steps:

step 1.1: starting a heater, and adjusting the power of the heater to a preset value;

step 1.2: calling a physical property program NIST REFPROP V8.0 of the supercritical carbon dioxide to calculate a pressure sensor and specific enthalpy h corresponding to 25 ℃;

step 1.3: calculating the temperature t of carbon dioxide corresponding to 0.1MPa and specific enthalpy h, if t is within the range of 10-50 ℃, keeping the heating power of the heater unchanged, and if t is less than 10 ℃, increasing the heating power of the heater; if t is higher than 50 ℃, reducing the heating power of the heater;

step 1.4: adjusting the opening of the control valve to enable the flow of the first flowmeter to reach a target value;

step 1.5: and (3) repeating the step 1.2 to the step 1.3, so that the temperature t of the carbon dioxide corresponding to the specific enthalpy h and the pressure of 0.1MPa is within the range of 10-50 ℃.

Step 2: the method comprises the following steps of monitoring the operation state of the dry gas seal after the compressor and the turbine are started and controlling the working states of the compressor and the turbine in time, wherein the method comprises the following specific steps:

step 2.1: the compressor/turbine rotor is increased to a target rotating speed according to a certain increasing rate;

step 2.2: monitoring the flow of the second flowmeter, and outputting a stop signal and controlling the compressor and the turbine to stop when the flow of the second flowmeter exceeds an allowable value;

step 2.3: the leak state of the labyrinth seal is monitored.

In conclusion, the high-efficiency sealing of the high-power high-rotating-speed supercritical carbon dioxide compressor and the turbine shaft end is realized by using dry gas sealing, the leakage of the compressor and the turbine is reduced by using labyrinth sealing when the dry gas sealing fails, and the safety of the unit is obviously improved; meanwhile, the automatic control of dry gas sealing air inlet is adopted, so that the phenomenon of carbon dioxide solidification in dry gas sealing is avoided, and the safe and stable operation of dry gas sealing is ensured.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.