Main air extractor with steam seal air extraction function

Abstract

The invention discloses a main air extractor with a steam seal air extraction function, and belongs to the technical field of vacuum air extraction. The problem that a steam seal air extractor and a main air extractor are arranged in a steam turbine unit at the same time, and arrangement miniaturization is affected is solved. Comprising the steps that high-speed steam enters a first-stage gas injection unit and a second-stage gas injection unit; high-speed steam in the first-stage gas injection unit sucks non-condensable gas which is introduced into an extraction opening of the condenser and comes from the condenser, and the non-condensable gas is discharged into the first-stage mixed gas cooling unit; high-speed steam in the second-stage gas injection unit sucks a first-stage uncondensed gas mixture in the first-stage mixed gas cooling unit and discharges the first-stage uncondensed gas mixture into the second-stage mixed gas cooling unit; gas leakage of the steam sealing system is sucked in through micro negative pressure of the second-stage mixed gas cooling unit and mixed with the gas mixture to form second-stage mixed gas, and the second-stage mixed gas is discharged after being cooled through the second-stage mixed gas cooling unit. The main air extractor has the steam seal air extraction function.

Description

TECHNICAL FIELD

[0001] The present application relates to a main air extractor with steam seal air extraction function, and belongs to the technical field of vacuum air extraction. BACKGROUND

[0002] Steam seal air extractor is an important auxiliary equipment of steam power system, which is widely used in power generation equipment in industrial sites such as power plants and chemical plants. Its main function is to extract steam or steam-air mixture from the shaft seal gap and other parts of the steam turbine, to establish the necessary vacuum operating environment for a series of devices such as high-pressure and low-pressure steam turbines, steam circulating water pumps, steam turbine generator sets and steam feed water pumps, so as to ensure the overall vacuum degree and operating efficiency of the unit.

[0003] Because the steam seal air extractor and the main air extractor each occupy a large space, they seriously restrict the demand for small-scale power generation. In addition, the existing generator set is generally equipped with only one steam seal air extractor. Once the steam seal air extractor fails or loses performance, or the auxiliary steam system pipeline fails and must be shut down for disposal, the vacuum degree will drop sharply, and the high-temperature shaft seal leakage will be discharged to the bearing box and other places, which will seriously affect the stability of the main steam turbine set and the steam turbine generator set, and further affect the safety of the entire power generation equipment, so enough attention must be paid.

[0004] The working principles of the main air extractor and the steam seal air extractor are similar. The main air extractor has the characteristics of high vacuum, low air extraction amount, and adjustable air extraction pressure. The steam seal air extractor has the characteristics of low vacuum, large air extraction amount, and adjustable air extraction pressure. The two have certain similarities. Therefore, through reasonable modification of the main air extractor, the main air extractor can have the function of the steam seal air extractor, or the main air extractor can run in the compatible steam seal air mode, realizing the adjustment of the vacuum and air extraction amount of the main air extractor to replace the existing emergency failure operation scheme of the steam seal air extractor.

[0005] At present, there is no mature modification scheme for the main air extractor in engineering, and the operation scheme or structural optimization design of the steam seal air extractor failure is also rare. SUMMARY

[0006] In view of the problem that the steam seal air extractor and the main air extractor are arranged at the same time in the steam turbine set, affecting the miniaturization, the present application provides a main air extractor with steam seal air extraction function.

[0007] The main air extractor with steam seal air extraction function of the present application comprises a main air extractor body and a steam seal system leakage connection pipe.

[0008] The main air extractor body comprises a steam inlet, a condenser air extraction port, an exhaust port, a first-stage gas induction unit, a first-stage mixed gas cooling unit, a second-stage gas induction unit and a second-stage mixed gas cooling unit.

[0009] The steam inlet is used for introducing high-speed steam, and the high-speed steam is introduced into the primary gas injection unit and the secondary gas injection unit through pipes respectively; the high-speed steam in the primary gas injection unit sucks the non-condensed gas from the condenser introduced into the condenser exhaust port, and discharges into the primary mixed gas cooling unit; the high-speed steam in the secondary gas injection unit sucks the primary non-condensed gas mixture in the primary mixed gas cooling unit, and discharges into the secondary mixed gas cooling unit;

[0010] The pressure of the gas mixture discharged from the secondary gas injection unit is lower than the atmospheric pressure, and a micro-negative pressure is formed in the secondary mixed gas cooling unit; the micro-negative pressure of the secondary mixed gas cooling unit is used to suck the steam seal system leakage in the steam seal system leakage connecting pipe, and the steam seal system leakage is mixed with the gas mixture in the secondary mixed gas cooling unit to form a secondary mixed gas, and after being cooled by the secondary mixed gas cooling unit, the secondary non-condensed gas mixture is discharged through the exhaust port.

[0011] According to the main air extractor with the steam seal air extraction function, the primary gas injection unit comprises a primary nozzle, a primary mixing chamber and a primary diffusion pipe, the high-speed steam sucks the non-condensed gas from the condenser introduced into the condenser exhaust port in the primary mixing chamber through the primary nozzle, and discharges into the primary mixed gas cooling unit through the primary diffusion pipe.

[0012] According to the main air extractor with the steam seal air extraction function, the primary mixed gas cooling unit comprises a primary cooling cavity and a primary cooling pipe bundle, and the gas discharged from the primary diffusion pipe is cooled in the primary cooling cavity through the primary cooling pipe bundle to obtain a primary non-condensed gas mixture.

[0013] According to the main air extractor with the steam seal air extraction function, the secondary gas injection unit comprises a secondary nozzle, a secondary mixing chamber and a secondary diffusion pipe, the high-speed steam sucks the primary non-condensed gas mixture in the secondary mixing chamber through the secondary nozzle, and discharges into the secondary mixed gas cooling unit through the secondary diffusion pipe.

[0014] According to the main air extractor with the steam seal air extraction function, the outlet pipe diameter of the secondary diffusion pipe is greater than the inlet pipe diameter, so that the pressure at the outlet of the secondary diffusion pipe is lower than the atmospheric pressure, and a micro-negative pressure is formed in the secondary mixed gas cooling unit.

[0015] According to the main air extractor with the steam seal air extraction function, the pressure at the outlet of the secondary diffusion pipe is 5-15kPa lower than the atmospheric pressure.

[0016] According to the main air extractor with the steam seal air extraction function, the primary cooling cavity and the secondary mixing chamber are communicated through an inter-stage connecting pipe.

[0017] According to the present invention, the main ejector with steam seal extraction function includes a secondary mixed gas cooling unit comprising a secondary cooling chamber and a secondary cooling tube bundle. The slight negative pressure in the secondary cooling chamber draws in the steam seal system leakage in the steam seal system leakage connection pipe and mixes it with the gas mixture discharged from the secondary diffuser to form a secondary mixed gas. After being cooled by the secondary cooling tube bundle, the secondary mixed gas is obtained as a secondary uncondensed gas mixture.

[0018] According to the present invention, the main ejector that also has the function of steam sealing and air extraction has a pressurization device installed in the exhaust port.

[0019] According to the present invention, the main ejector that also has the function of steam seal extraction is provided with a valve on the leakage connection pipe of the steam seal system.

[0020] The beneficial effects of this invention are as follows: This invention, combined with practical engineering requirements, provides a modification scheme for the main ejector, offering not only new ideas for miniaturized auxiliary equipment design but also a solution for uninterrupted operation switching in case of steam seal ejector failure. Considering the miniaturization and reliability requirements of steam power generation equipment, this invention optimizes the structure of the main ejector for compatibility, enabling it to also perform steam seal ejection functions. It can replace the steam seal ejector or temporarily replace it in case of failure, ensuring continued vacuum operation of the equipment through emergency switching.

[0021] This invention modifies the structure of the secondary gas ejector unit to create a negative pressure environment at its outlet, enabling the main ejector to also function as a steam seal ejector. This effectively reduces the overall space occupied by auxiliary equipment and facilitates miniaturized design of auxiliary equipment. Attached Figure Description

[0022] Fig. 1 This is a schematic diagram of the main ejector with both steam sealing and ejection functions as described in this invention.

[0023] Fig. 2 This is a pressure distribution diagram of the gas flow section within the secondary gas ejector unit;

[0024] Fig. 3 This is a schematic diagram of the operating principle of the main ejector, which also has the function of steam sealing and air extraction. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Specific Implementation Method 1: Combination Figs. 1 to 3As shown, the present invention provides a main ejector that also has the function of steam seal extraction, including a main ejector body and a steam seal system leakage connection pipe 200.

[0027] The main ejector body includes a steam inlet 110, a condenser ejector port 120, an exhaust port 130, a primary gas ejector unit, a primary mixed gas cooling unit, a secondary gas ejector unit, and a secondary mixed gas cooling unit.

[0028] Steam inlet 110 is used to introduce high-speed steam, which enters the primary gas ejector unit and the secondary gas ejector unit through pipelines respectively; the high-speed steam in the primary gas ejector unit draws in the non-condensable gas from the condenser introduced into the condenser exhaust port 120 and discharges it into the primary mixed gas cooling unit; the high-speed steam in the secondary gas ejector unit draws in the primary non-condensable gas mixture in the primary mixed gas cooling unit and discharges it into the secondary mixed gas cooling unit.

[0029] The pressure of the gas mixture discharged from the secondary gas ejector unit is lower than atmospheric pressure, forming a slight negative pressure in the secondary mixed gas cooling unit. The slight negative pressure of the secondary mixed gas cooling unit is used to draw in the leaking gas from the steam seal system in the leaking connection pipe 200, and mix it with the gas mixture in the secondary mixed gas cooling unit to form a secondary mixed gas. After being cooled by the secondary mixed gas cooling unit, the secondary uncondensed gas mixture is discharged through the exhaust port 130.

[0030] The high-speed steam source is generally the turbine exhaust port, usually low-pressure or medium-pressure exhaust.

[0031] Furthermore, the primary gas ejector unit includes a primary nozzle 141, a primary mixing chamber 142, and a primary diffuser 143. High-speed steam draws in non-condensable gas from the condenser through the primary nozzle 141 in the primary mixing chamber 142, and discharges it through the primary diffuser 143 into the primary mixed gas cooling unit.

[0032] The primary mixed gas cooling unit includes a primary cooling chamber 151 and a primary cooling tube bundle 152. The gas discharged from the primary diffuser 143 is cooled by the primary cooling tube bundle 152 in the primary cooling chamber 151 to obtain a primary uncondensed gas mixture.

[0033] Furthermore, the secondary gas ejector unit includes a secondary nozzle 161, a secondary mixing chamber 162, and a secondary diffuser 163. High-speed steam draws in the primary uncondensed gas mixture through the secondary nozzle 161 in the secondary mixing chamber 162, and discharges it through the secondary diffuser 163 into the secondary mixed gas cooling unit.

[0034] The outlet diameter of the secondary diffuser 163 is larger than the inlet diameter, causing the pressure at the outlet of the secondary diffuser 163 to be lower than atmospheric pressure, thus creating a slight negative pressure within the secondary mixed gas cooling unit. Because the pressure on the main ejector side of the steam seal system leakage connection pipe 200 is lower than the pressure on the steam seal system side, the leaking gas from the steam seal system is drawn into the secondary cooling chamber 171.

[0035] The shape and length of the secondary diffuser 163 need to be calculated using fluid dynamics to ensure that the pressure near the leaking connection pipe 200 of the steam sealing system is slightly negative.

[0036] As an example, the pressure at the outlet of the secondary diffuser 163 is 5-15 kPa lower than atmospheric pressure, that is, the pressure at the outlet of the secondary diffuser 163 is 85-95 kPa.

[0037] The primary cooling chamber 151 and the secondary mixing chamber 162 are connected by an interstage connecting pipe 300.

[0038] The secondary mixed gas cooling unit includes a secondary cooling chamber 171 and a secondary cooling tube bundle 172. The slight negative pressure in the secondary cooling chamber 171 draws in the leaking gas from the steam sealing system in the steam sealing system leakage connection pipe 200, and mixes it with the gas mixture discharged from the secondary diffuser 163 to form a secondary mixed gas. After being cooled by the secondary cooling tube bundle 172, the secondary uncondensed gas mixture is obtained.

[0039] In this embodiment, the design of the primary gas ejector unit is the same as that of a conventional main ejector. The secondary diffuser 163 is a modification of the original diffuser. Fig. 2 As shown, in the existing design, the exhaust pressure formed at the diffuser outlet by the steam and air mixture is... greater than atmospheric pressure This creates positive pressure, ensuring a slight positive pressure after passing through the secondary cooling chamber and allowing for smooth discharge from the main ejector. In this embodiment, to achieve both steam seal extraction and other functions, the secondary diffuser is modified to increase the exhaust pressure of the steam-air mixture after flowing through the secondary diffuser 163. Less than atmospheric pressure This creates a negative pressure, ensuring a certain siphon effect. At the leakage outlet of the corresponding steam seal system leakage connection pipe 200, since the pressure is lower than the pressure inside the steam seal system, it is possible to extract air from the steam seal system. Fig. 2 middle The outlet pressure of the secondary nozzle 161, This refers to the suction pressure.

[0040] The secondary cooling tube bundle 172 needs to have an increased number of tube rows based on thermal calculations to increase the heat exchange area and ensure steam cooling requirements. The secondary cooling tube bundle 172 can employ heat transfer enhancement technologies, including but not limited to increasing the heat exchange area and using high-performance heat exchange tubes. The heat exchange area of ​​the secondary cooling tube bundle 172 must be designed according to the maximum heat exchange requirement, i.e., calculated based on the sum of steam leakage from the steam seal and the secondary mixed gas from the original main ejector.

[0041] The secondary cooling tube bundle 172 adopts a high-performance heat transfer design, including but not limited to using various special-shaped tubes such as threaded tubes, annular finned tubes, and finned tubes.

[0042] A booster device is installed inside the exhaust port 130.

[0043] Since the steam-air mixture is under negative pressure in the secondary cooling chamber 171, which is lower than the discharge pressure, a booster device, such as an axial flow fan, needs to be added to the exhaust port 130 to achieve gas discharge.

[0044] A valve is installed on the leak connection pipe 200 of the steam sealing system.

[0045] The valve can be used to deal with emergency shutdowns of the steam seal ejector. After the steam seal ejector fails and shuts down, the valve can be temporarily opened to achieve a switchover without shutting down the system.

[0046] A simplified schematic diagram of the operation process of this invention is shown below. Fig. 3 As shown, the main ejector uses the slight negative pressure generated by the secondary gas ejector unit to draw in the leaking gas from the steam sealing system, and discharges the residual gas through the secondary mixed gas cooling unit and the pressurization device.

[0047] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A main ejector that also functions as a steam seal ejector, characterized in that, Includes the main ejector body and the leak connection pipe (200) of the steam sealing system. The main ejector body includes a steam inlet (110), a condenser ejector port (120), an exhaust port (130), a primary gas ejector unit, a primary mixed gas cooling unit, a secondary gas ejector unit, and a secondary mixed gas cooling unit. The steam inlet (110) is used to introduce high-speed steam, which enters the primary gas ejector unit and the secondary gas ejector unit through pipelines respectively. The high-speed steam in the primary gas ejector unit draws in the non-condensable gas from the condenser introduced into the condenser exhaust port (120) and discharges it into the primary mixed gas cooling unit. The high-speed steam in the secondary gas ejector unit draws in the primary non-condensable gas mixture in the primary mixed gas cooling unit and discharges it into the secondary mixed gas cooling unit. The pressure of the gas mixture discharged from the secondary gas ejector unit is lower than the atmospheric pressure, forming a slight negative pressure in the secondary mixed gas cooling unit; the slight negative pressure of the secondary mixed gas cooling unit is used to draw in the gas seal system leakage in the gas seal system leakage connection pipe (200), and mix it with the gas mixture in the secondary mixed gas cooling unit to form a secondary mixed gas. After being cooled by the secondary mixed gas cooling unit, the secondary uncondensed gas mixture is discharged through the exhaust port (130).

2. The main ejector with both steam sealing and ejection functions according to claim 1, characterized in that, The primary gas ejector unit includes a primary nozzle (141), a primary mixing chamber (142), and a primary diffuser (143). High-speed steam draws in non-condensable gas from the condenser through the primary nozzle (141) in the primary mixing chamber (142) and discharges it through the primary diffuser (143) into the primary mixed gas cooling unit.

3. The main ejector with both steam seal and extraction functions according to claim 2, characterized in that, The primary mixed gas cooling unit includes a primary cooling chamber (151) and a primary cooling tube bundle (152). The gas discharged from the primary diffuser (143) is cooled by the primary cooling tube bundle (152) in the primary cooling chamber (151) to obtain a primary uncondensed gas mixture.

4. The main ejector with both steam sealing and extraction functions according to claim 3, characterized in that, The secondary gas ejector unit includes a secondary nozzle (161), a secondary mixing chamber (162), and a secondary diffuser (163). High-speed steam draws in the primary uncondensed gas mixture through the secondary nozzle (161) in the secondary mixing chamber (162) and discharges it through the secondary diffuser (163) into the secondary mixed gas cooling unit.

5. The main ejector with both steam sealing and ejection functions according to claim 4, characterized in that, The outlet diameter of the secondary diffuser (163) is larger than the inlet diameter, so that the pressure at the outlet of the secondary diffuser (163) is lower than the atmospheric pressure, forming a slight negative pressure in the secondary mixed gas cooling unit.

6. The main ejector with both steam seal and extraction functions according to claim 5, characterized in that, The pressure at the outlet of the secondary diffuser (163) is 5-15 kPa lower than atmospheric pressure.

7. The main ejector with both steam sealing and extraction functions according to claim 4, characterized in that, The primary cooling chamber (151) and the secondary mixing chamber (162) are connected by an interstage connecting pipe (300).

8. The main ejector with both steam seal and ejection functions according to claim 7, characterized in that, The secondary mixed gas cooling unit includes a secondary cooling chamber (171) and a secondary cooling tube bundle (172). The slight negative pressure in the secondary cooling chamber (171) draws in the leaking gas from the steam sealing system in the steam sealing system leakage connection pipe (200) and mixes it with the gas mixture discharged from the secondary diffuser (163) to form a secondary mixed gas. After being cooled by the secondary cooling tube bundle (172), the secondary uncondensed gas mixture is obtained.

9. The main ejector with both steam sealing and ejection functions according to claim 1, characterized in that, A booster device is installed inside the exhaust port (130).

10. The main ejector with both steam seal and ejection functions according to claim 1, characterized in that, A valve is installed on the leak connection pipe (200) of the steam sealing system.

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