Online cleaning system of steam turbine

Abstract

The utility model provides a steam turbine online cleaning system which comprises a main steam pipeline, a steam turbine, a condenser and a water spraying cooling device, a first isolation valve and a second isolation valve are sequentially arranged on the main steam pipeline in the steam flowing direction, the first isolation valve is connected with a first bypass pipeline in parallel, and a first bypass valve is arranged on the first bypass pipeline; the second isolating valve is connected with a second bypass pipeline in parallel, and a second bypass valve is arranged on the second bypass pipeline. The main steam pipeline is further provided with a first warm pipe emptying valve and a second warm pipe emptying valve. A heat preservation dismantling section is arranged on the portion, between the second isolating valve and the second warm pipe emptying valve, of the main steam pipeline, a water spraying opening of the water spraying cooling device is located over the heat preservation dismantling section, and a pipe wall remote transmission temperature measuring point and a main pipeline pressure sensor are arranged at the position behind the heat preservation dismantling section. Efficient online cleaning of the steam turbine is achieved.

Description

Technical Field

[0001] This application relates to the technical field of steam turbines, and particularly to an on-line cleaning system for steam turbines. Background Art

[0002] A steam turbine, also known as a steam turbine engine, is a rotary steam power device. High-temperature and high-pressure steam passes through a fixed nozzle to become an accelerated air flow and then jets onto the blades, causing the rotor equipped with the blade row to rotate and perform external work at the same time. A steam turbine is the main equipment in modern thermal power plants and is also used in the metallurgical industry, chemical industry, and ship power plants. An air separation steam turbine is a device that can separate gases. Its working principle is based on the different molecular sizes and boiling points of gases. By heating and compressing air, it is converted into high-temperature and high-pressure gas, and a series of filters, membranes, and adsorbents are used to separate it into different gases to achieve the purpose of purification or production of gases such as oxygen, nitrogen, and argon.

[0003] After superheated steam with various impurities enters the steam turbine, due to the decrease in pressure and temperature, the solubility of impurity salts in the steam decreases with the decrease in pressure and precipitates in solid state, depositing on the steam flow path of the steam turbine to form scale, generally referred to as steam turbine salt deposition.

[0004] If the scale inside the steam turbine is not cleaned in time, it will lead to a decrease in the steam flow area and the steam inlet volume, and further lead to a decrease in the power and efficiency of the steam turbine.

[0005] The traditional cleaning method is manual cleaning, which not only has a high labor intensity, but also requires the steam turbine to be shut down and the cylinder to be opened for cleaning. The disassembly and assembly steps are cumbersome and the cleaning time is long, resulting in a very large economic loss. Utility Model Content

[0006] This application provides an on-line cleaning system for steam turbines to solve the above problems mentioned in the background art.

[0007] This application provides an on-line cleaning system for steam turbines, including: a main steam pipeline, a steam turbine, a condenser, and a water spray cooling device.

[0008] The outlet end of the main steam pipeline is connected to the steam inlet of the steam turbine, and the exhaust port of the steam turbine is connected to the steam inlet of the condenser.

[0009] A first isolation valve and a second isolation valve are sequentially arranged on the main steam pipeline near the steam inlet end along the steam flow direction. A first bypass pipeline is arranged in parallel with the first isolation valve, and a first bypass valve is arranged on the first bypass pipeline. A second bypass pipeline is arranged in parallel with the second isolation valve, and a second bypass valve is arranged on the second bypass pipeline.

[0010] A first warm-up drain valve is provided on the main steam pipeline before the first isolation valve, and a second warm-up drain valve is provided on the main steam pipeline between the second isolation valve and the steam turbine.

[0011] An insulation removal section is provided on the main steam pipeline between the second isolation valve and the second warm-up drain valve. The water spray nozzle of the water spray cooling device is located directly above the insulation removal section. A remote wall temperature measurement point and a main pipeline pressure sensor are provided on the main steam pipeline after the insulation removal section.

[0012] Optionally, a plurality of drain pipes are further provided on the main steam pipeline, including: an intermediate isolation valve drain pipe between the first isolation valve and the second isolation valve, a first drain valve is provided on the intermediate isolation valve drain pipe, a post-isolation valve drain pipe is provided between the second isolation valve and the insulation removal section, a second drain valve is provided on the post-isolation valve drain pipe, a third drain pipe is provided between the remote wall temperature measurement point and the steam turbine, and a third drain valve is provided on the third drain pipe.

[0013] Optionally, the length of the insulation removal section is 15 - 20m.

[0014] Optionally, the cleaning system further includes a water circulation device, which includes a spray water collection tank, a condensate collection tank, a water treatment device and a circulation water pump. The spray water collection tank is located below the insulation removal section. The inlet of the condensate collection tank is connected to the outlet of the condenser. The outlets of the spray water collection tank and the condensate collection tank are both connected to the water treatment device. A circulation water pump is connected between the purified water outlet of the water treatment device and the inlet of the water spray cooling device.

[0015] Optionally, the water treatment device includes a filter screen filtration chamber, an activated carbon filtration chamber and a purified water chamber connected in sequence.

[0016] The outlets of the spray water collection tank and the condensate collection tank are both connected to the filter screen filtration chamber, and the outlet of the purified water chamber is connected to the inlet of the water spray cooling device.

[0017] Optionally, a heat preservation barrel is sleeved on the outer periphery of the insulation removal section. Cooling water inlets and cooling water outlets are respectively provided at both ends of the heat preservation barrel. A cooling water regulating valve is connected between the cooling water inlet and the outlet of the water spray cooling device, and the cooling water outlet is connected to the inlet of the spray water collection tank.

[0018] Optionally, a heat preservation barrel pressure sensor is provided inside the heat preservation barrel, and a negative pressure vacuum pump is also connected to the heat preservation barrel.

[0019] The on-line cleaning system for steam turbine provided by this application realizes the efficient on-line cleaning of the steam turbine. Compared with the prior art, it has the following beneficial effects:

[0020] (1) Superheated steam is provided through the main steam pipeline. Utilizing the property that scale dissolves in water, and at the same time, the superheated steam is cooled through a water spraying cooling device to reduce the temperature of the superheated steam, increase the liquid water content in the superheated steam, thereby increasing the solubility of the scale, achieving the purpose of rapid scale removal, and realizing the on-line cleaning of the steam turbine. A first bypass pipeline is arranged in parallel at both ends of the first isolation valve, and a second bypass pipeline is arranged in parallel at both ends of the second isolation valve. At the same time, the diameters of the first bypass pipeline and the second bypass pipeline are the same and smaller than the diameter of the main steam pipeline. By setting the first bypass valve and the second bypass valve, it is used to adjust the steam input during the cleaning process, which is beneficial to the rapid and accurate control of the cleaning system, improving the convenience of use and the operating stability of the cleaning system. At the same time, the setting of the water spraying cooling device can also adjust the pressure in the main steam pipeline, achieve the balance of pressure and temperature, ensure the safe and stable operation of the cleaning system while cleaning the steam turbine. It not only does not require uncovering the cover of the steam turbine for cleaning, improving the cleaning efficiency, but also improves the operating efficiency and stability of the steam turbine.

[0021] (2) By arranging a plurality of drain pipes on the main steam pipeline, the condensate in the main steam pipeline can be discharged quickly and timely, preventing the accumulation of condensate, being beneficial to the uniform distribution of temperature and pressure in the main steam pipeline, avoiding the phenomenon of excessive local pressure in the main steam pipeline, and contributing to the efficient and stable operation of the cleaning system.

[0022] (3) By setting a heat preservation barrel, when the steam turbine is being cleaned, cooling water is introduced through the cooling water inlet to cool the superheated steam to increase the liquid water content and improve the dissolution efficiency of the scale. And the heat-exchanged cooling water is transported to the spray water collection tank through the cooling water outlet. When the steam turbine is not being cleaned but operating normally to do work, the heat preservation barrel can play a certain heat preservation role for the heat preservation removal section, reducing the heat loss of the steam. At the same time, the heat preservation barrel is connected to a negative pressure vacuum pump. After the cleaning of the steam turbine is completed, the inside of the heat preservation barrel is evacuated to form a certain vacuum degree between the inside of the heat preservation barrel and the heat preservation removal section, greatly reducing the air content in the heat preservation barrel, reducing the heat transfer medium between the inside of the main steam pipeline and the outside world. Then, when the superheated steam flows through the heat preservation removal section during the normal operation of the steam turbine, it can maintain the temperature, reduce the heat loss, and thus save production costs.

[0023] (4) This application solves the problem of scale accumulation inside the steam turbine, does not require frequent disassembly and assembly of the steam turbine, improves the cleaning efficiency of the steam turbine, and improves the operating efficiency and stability of the steam turbine. At the same time, compared with the cleaning method that requires uncovering the cylinder, the cleaning effect is better and it is worthy of promotion in the industry. Brief Description of the Drawings

[0024] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Schematic structural diagram of the on-line cleaning system for a steam turbine provided by an embodiment of the present application;

[0026] Figure 2 Schematic structural diagram of the on-line cleaning system for a steam turbine provided by another embodiment of the present application;

[0027] Figure 3 Schematic structural diagram of the on-line cleaning system for a steam turbine provided by still another embodiment of the present application;

[0028] Figure 4 Schematic structural diagram of the water circulation device and heat preservation barrel provided by an embodiment of the present application;

[0029] Explanation of reference numerals:

[0030] 1: Main steam pipeline, 2: Steam turbine, 3: Condenser, 4: Spray cooling device, 6: Water treatment device, 7: Circulation water pump, 110: First isolation valve, 120: Second isolation valve, 130: First bypass pipeline, 131: First bypass valve, 140: Second bypass pipeline, 141: Second bypass valve, 150: First warm-up drain valve, 160: Second warm-up drain valve, 170: Heat preservation removal section, 171: Spray water collection tank, 180: Remote temperature measurement point on the pipe wall, 190: Main pipeline pressure sensor, 310: Condensate collection tank, 410: Cooling water regulating valve, 510: Isolation valve intermediate drain pipe, 511: First drain valve, 520: Isolation valve rear drain pipe, 521: Second drain valve, 530: Third drain pipe, 531: Third drain valve, 610: Filter screen filtration chamber, 620: Activated carbon filtration chamber, 630: Clean water chamber, 710: Heat preservation barrel, 720: Water inlet, 730: Water outlet, 740: Pressure sensor, 750: Negative pressure vacuum pump. Detailed implementation manners

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following clearly and completely describes the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts also belong to the scope of protection of the present application.

[0032] Such asFigure 1 As shown in Figure 1 , the present application provides an on-line cleaning system for a steam turbine, including: a main steam pipeline 1, a steam turbine 2, a condenser 3 and a spray cooling device 4.

[0033] The outlet end of the main steam pipeline 1 is communicated with the steam inlet of the steam turbine 2, and the exhaust port of the steam turbine 2 is communicated with the steam inlet of the condenser 3.

[0034] A first isolation valve 110 and a second isolation valve 120 are sequentially arranged on the main steam pipeline 1 near the steam inlet end along the steam flow direction. A first bypass pipeline 130 is arranged in parallel with the first isolation valve 110, and a first bypass valve 131 is arranged on the first bypass pipeline 130. A second bypass pipeline 140 is arranged in parallel with the second isolation valve 120, and a second bypass valve 141 is arranged on the second bypass pipeline 140.

[0035] A first warm-up and vent valve 150 is arranged on the main steam pipeline 1 before the first isolation valve 110, and a second warm-up and vent valve 160 is arranged on the main steam pipeline 1 between the second isolation valve 120 and the steam turbine 2.

[0036] An insulation removal section 170 is arranged on the main steam pipeline 1 between the second isolation valve 120 and the second warm-up and vent valve 160. The water spray outlet of the spray cooling device 4 is located directly above the insulation removal section 170. A remote wall temperature measuring point 180 and a main pipeline pressure sensor 190 are arranged on the main steam pipeline 1 after the insulation removal section 170.

[0037] Specifically, in this embodiment, an air separation steam turbine is taken as an example to explain the principle of on-line cleaning of the steam turbine. In this embodiment, the steam turbine 2 is respectively connected with an air compressor and a booster through couplings.

[0038] The steam inlet end of the main steam pipeline 1 is connected to the steam network for providing superheated steam. When the steam turbine 2 is operating normally, superheated steam is introduced to supply heat energy to the steam turbine 2, enabling the steam turbine 2 to convert heat energy into mechanical energy for doing work and driving the air compressor and booster to operate, so as to achieve the purpose of separating air and producing gases such as oxygen, nitrogen, and argon. When the steam turbine 2 needs to be cleaned, superheated steam is still provided through the main steam pipeline 1. Utilizing the characteristic that the scale dissolves in water, at the same time, the superheated steam is cooled by the water spraying and cooling device 4 to reduce the temperature of the superheated steam, increase the liquid moisture in the superheated steam, thereby increasing the solubility of the scale and achieving the purpose of rapid scale removal to realize the on-line cleaning of the steam turbine 2. At the same time, the setting of the water spraying and cooling device 4 can also adjust the pressure in the main steam pipeline 1 to achieve the balance of pressure and temperature, ensuring the safe and stable operation of the cleaning system while cleaning the steam turbine 2. After the hot steam is cleaned in the steam turbine 2, it enters the condenser 3 through the exhaust port of the steam turbine 2 for condensation. Condensate is obtained in the condenser 3 and is transported to the wastewater treatment station for treatment or transported to the water treatment device for purification and then reused. In this way, not only does it not require uncovering the cover of the steam turbine 2 for cleaning, improving the cleaning efficiency, but also improving the operating efficiency and stability of the steam turbine 2.

[0039] The first isolation valve 110 and the second isolation valve 120 on the main steam pipeline 1 are used to adjust the flow rate of the superheated steam when the steam turbine 2 is operating normally. When the steam turbine 2 is operating normally, the required amount of superheated steam is large, and the diameter of the main steam pipeline 1 is large. However, when the steam turbine 2 is being cleaned, the required amount of superheated steam is less than that during normal operation for doing work. Therefore, in order to facilitate the accurate and rapid adjustment of the input amount of superheated steam during the cleaning process, a first bypass pipeline 130 is arranged in parallel at both ends of the first isolation valve 110, and a second bypass pipeline 140 is arranged in parallel at both ends of the second isolation valve 120. At the same time, the diameters of the first bypass pipeline 130 and the second bypass pipeline 140 are the same and smaller than the diameter of the main steam pipeline 1. A first bypass valve 131 is arranged on the first bypass pipeline 130, and a second bypass valve 141 is arranged on the second bypass pipeline 140 for adjusting the input amount of steam during the cleaning process, which is beneficial to the rapid and accurate control of the cleaning system and improves the usability and operating stability of the cleaning system.

[0040] Before cleaning the steam turbine, the pipeline needs to be heated so that the main steam pipeline 1, valves, flanges and other components are evenly heated and slowly expanded during the heating process to reach the cleaning working temperature, so as to avoid excessive thermal stress caused by rapid temperature changes. Ensure that there is no additional thermal stress on the pipelines and valves, thereby preventing damage or deformation of components due to excessive stress. When heating the pipes, superheated steam is introduced through the main steam pipeline 1, and the first heating pipe vent valve 150 and the second heating pipe vent valve 160 are opened at the same time. During the heating process, a part of the steam is discharged to release the pressure, so that the superheated steam can circulate quickly in the main steam pipeline 1, thereby improving the heating efficiency, saving time, and thus improving the cleaning efficiency of the steam turbine.

[0041] At the same time, the outer surface of the main steam pipe 1 is wrapped with an insulation layer to reduce heat loss during steam transportation. The present application provides an insulation removal section 170 on the main steam pipe 1 between the second isolation valve 120 and the second heating pipe vent valve 160. The water spray outlet of the water spray cooling device 4 is located directly above the insulation removal section 170. During the cleaning process, water is sprayed on the insulation removal section 170 through the water spray cooling device 4 to cool the steam in the main steam pipe 1, adjust the pressure and temperature balance in the main steam pipe 1, and at the same time reduce the temperature of the superheated steam, increase the liquid water in the superheated steam, thereby increasing the solubility of the deposited scale and achieving the purpose of rapid scale removal.

[0042] A pipe wall remote temperature measuring point 180 and a main pipe pressure sensor 190 are provided on the main steam pipe 1 after the insulation removal section 170, for detecting the temperature and pressure of the steam entering the steam turbine 2 in the main steam pipe 1, and adjusting the opening of each valve according to the readings of the pipe wall remote temperature measuring point 180 and the main pipe pressure sensor 190 to ensure the balance of temperature and pressure in the main steam pipe 1 and the stable operation of the cleaning system.

[0043] Through the above solution, the present application realizes the online cleaning of the steam turbine. Superheated steam is provided through the main steam pipeline. Utilizing the property that the scale dissolves in water, and at the same time, the superheated steam is cooled by a water spraying cooling device to reduce the temperature of the superheated steam, increase the liquid moisture in the superheated steam, thereby increasing the solubility of the scale, achieving the purpose of rapid scale removal, and realizing the online cleaning of the steam turbine. A first bypass pipeline is arranged in parallel at both ends of the first isolation valve, and a second bypass pipeline is arranged in parallel at both ends of the second isolation valve. At the same time, the diameters of the first bypass pipeline and the second bypass pipeline are the same and smaller than the diameter of the main steam pipeline. By setting the first bypass valve and the second bypass valve, it is used to adjust the input amount of steam during the cleaning process, which is beneficial to the rapid and accurate control of the cleaning system, improving the usability and operation stability of the cleaning system. At the same time, the setting of the water spraying cooling device can also adjust the pressure in the main steam pipeline, achieve the balance of pressure and temperature, ensure the safe and stable operation of the cleaning system while cleaning the steam turbine. It not only does not require uncovering the steam turbine for cleaning, improving the cleaning efficiency, but also improves the operation efficiency and stability of the steam turbine.

[0044] As Figure 2 shown, optionally, a plurality of drain pipes are further provided on the main steam pipeline 1, including: an intermediate isolation valve drain pipe 510 located between the first isolation valve 110 and the second isolation valve 120, a first drain valve 511 is provided on the intermediate isolation valve drain pipe 510, a post-isolation valve drain pipe 520 is provided between the second isolation valve 120 and the insulation removal section 170, a second drain valve 521 is provided on the post-isolation valve drain pipe 520, a third drain pipe 530 is provided between the wall remote temperature measurement point 180 and the steam turbine 2, and a third drain valve 531 is provided on the third drain pipe 530.

[0045] Specifically, the drain pipes are provided to drain the liquid phase water in the main steam pipeline 1, prevent the condensate formed by the condensation of the steam in the main steam pipeline 1 from accumulating in the pipeline, causing a water hammer phenomenon, and further damaging the impeller of the steam turbine 2. Timely drainage can prevent the condensate from entering the steam turbine 2 and protect the normal operation of the steam turbine 2.

[0046] The post-isolation valve drain pipe 520 is located after the connection position of the second bypass pipeline 140 and the main steam pipeline 1 to ensure the steam flow and efficient cooling of the steam. The intermediate isolation valve drain pipe 510, the post-isolation valve drain pipe 520, and the third drain pipe 530 can quickly drain the condensate in the main steam pipeline 1 in a timely manner by providing a plurality of drain pipes on the main steam pipeline 1, prevent the accumulation of condensate, facilitate the uniform distribution of temperature and pressure in the main steam pipeline 1, avoid the phenomenon of excessive local pressure in the main steam pipeline 1, and contribute to the efficient and stable operation of the cleaning system.

[0047] Furthermore, multiple third drain pipes 530 are provided between the remote temperature measurement point 180 on the pipe wall and the steam turbine 2. The distance between each third drain pipe 530 is determined according to the actual working conditions, further realizing the timely discharge of the condensate in the main steam pipe 1 and improving the safety of system operation.

[0048] Optionally, the length of the insulation removal section 170 is 15 - 20 m.

[0049] Specifically, the outer surface of the main steam pipe 1 is wrapped with a thermal insulation layer to reduce heat loss during steam transportation. In this cleaning system, the temperature of the superheated steam is reduced to increase the liquid moisture in the superheated steam, thereby increasing the solubility of the scale and achieving the purpose of rapid scale removal. Therefore, by setting the insulation removal section 170, the water in the water spraying cooling device 4 is used to cool the superheated steam in the main steam pipe 1, increasing the liquid moisture in the steam and improving the scale removal efficiency.

[0050] If the length of the insulation removal section 170 is too short or too long, it will be difficult to control the cooling of the steam. Controlling the insulation removal section 170 at an appropriate length is beneficial to system control, avoids steam loss, and prevents heat waste.

[0051] As Figure 3 shown, optionally, the cleaning system further includes a water circulation device. The water circulation device includes a spray water collection tank 171, a condensate collection tank 310, a water treatment device 6, and a circulation water pump 7. The spray water collection tank 171 is located below the insulation removal section 170. The inlet of the condensate collection tank 310 is communicated with the outlet of the condenser 3. The outlets of the spray water collection tank 171 and the condensate collection tank 310 are both communicated with the water treatment device 6. A circulation water pump 7 is connected between the purified water outlet of the water treatment device 6 and the inlet of the water spraying cooling device 4.

[0052] Specifically, the water circulation device is used to recover the spray water obtained by exchanging heat between the water in the water spraying cooling device 4 and the insulation removal section 170, and the condensate in the condenser 3, and purify them through the water treatment device 6. The purified water is transported back to the water spraying cooling device 4 through the circulation water pump 7, improving the reuse rate of water, reducing the load on the factory wastewater station, reducing sewage discharge, avoiding water resource waste, and saving production costs.

[0053] The water in the water spraying cooling device 4 after exchanging heat with the insulation removal section 170 is collected in the spray water collection tank 171, and the condensate in the condenser 3 is collected in the condensate collection tank 310, and they are respectively transported to the water treatment device 6 for purification. After removing the impurities in the water, they are transported to the water spraying cooling device 4 for reuse.

[0054] As Figure 4As shown, optionally, the water processor 6 includes a filter screen filtration chamber 610, an activated carbon filtration chamber 620, and a purified water chamber 630 that are connected in sequence.

[0055] The water outlets of the spray water collection tank 171 and the condensate collection tank 310 are both connected to the filter screen filtration chamber 610, and the outlet of the purified water chamber 630 is connected to the water inlet of the spray water cooling device 4.

[0056] Specifically, the condensate may contain scoured solid scale. The filter screen filtration chamber 610 first removes solid impurities from the collected spray water and condensate through the filter screen filtration chamber 610, and then performs adsorption filtration through the activated carbon filtration chamber 620 to remove fine impurities therein, achieving the effect of further purification and avoiding clogging the pump body or pipeline during recycling.

[0057] As Figure 4 As shown, optionally, a heat preservation barrel 710 is sleeved on the outer periphery of the heat preservation removal section 170. Cooling water inlets 720 and cooling water outlets 730 are respectively arranged at both ends of the heat preservation barrel 710. A cooling water regulating valve 410 is connected between the cooling water inlet 720 and the outlet of the spray water cooling device 4, and the cooling water outlet 730 is connected to the inlet of the spray water collection tank 171.

[0058] Specifically, when the steam turbine 2 is being cleaned, the heat preservation barrel 710 is used to introduce cooling water through the cooling water inlet 720 to cool the superheated steam to increase the liquid moisture content and improve the dissolution efficiency of the scale. The heat-exchanged cooling water is then transported to the spray water collection tank 171 through the cooling water outlet 730. When the steam turbine is not being cleaned but is operating normally to do work, the heat preservation barrel 710 can play a certain heat preservation role for the heat preservation removal section 170, reducing the heat loss of the steam.

[0059] Optionally, a heat preservation barrel pressure sensor 740 is arranged inside the heat preservation barrel 710, and the heat preservation barrel 710 is also connected to a negative pressure vacuum pump 750.

[0060] Specifically, after the steam turbine cleaning is completed or during normal operation and power generation, the negative pressure vacuum pump 750 is started to evacuate the negative pressure inside the heat preservation barrel 710, so that a certain degree of vacuum is formed in the space between the inside of the heat preservation barrel 710 and the heat preservation removal section 170, greatly reducing the air content in the heat preservation barrel 710 and reducing the heat transfer medium between the main steam pipeline 1 and the outside world. Furthermore, when the superheated steam flows through the heat preservation removal section 170 during the normal operation of the steam turbine 2, the temperature can be maintained, heat loss can be reduced, and thus production costs can be saved. The space between the inside of the heat preservation barrel 710 and the heat preservation removal section 170 maintains a vacuum degree below 3 kPa, which is specifically determined according to the materials of the heat preservation barrel 710 and the pipe body of the heat preservation removal section 170 under actual working conditions. Moreover, compared with disassembling and assembling the heat preservation materials of the heat preservation removal section 170 before and after each cleaning, the settings of the heat preservation barrel 710, the pressure sensor 740, and the negative pressure vacuum pump 750 are more convenient, further improving the cleaning efficiency of the steam turbine.

[0061] The on-line cleaning system of the steam turbine of the present application includes the following steps during operation:

[0062] (1) Steam turbine steam isolation: Completely close the first isolation valve, the second isolation valve, the first bypass valve, the second bypass valve, the first warm pipe vent valve, and the first drain valve, fully open the second warm pipe vent valve and the second drain valve, and let the steam turbine cylinder body naturally cool down to below 80 °C, and detect the conductivity and silica content of the condensate in the condenser before cleaning.

[0063] (2) Steam warm-up: Adjust the second warm pipe vent valve to an opening degree of 10 - 90%, adjust the second drain valve to an opening degree of 10 - 90%, and adjust the third drain valve to an opening degree of 10 - 50%.

[0064] Then adjust the first bypass valve and the second bypass valve to an opening degree of 10 - 50%, and start to warm up the main steam pipeline until the pressure value of the main pipeline pressure sensor is 2.1 - 2.2 MPa and the temperature value of the remote temperature measurement point on the pipe wall is 220 - 230 °C, and the warm-up is completed.

[0065] (3) On-line cleaning: Start the steam turbine, control the steam temperature to be superheated by 20 - 30 °C under the corresponding pressure, and at the same time perform periodic speed-up and speed-down adjustment on the steam turbine to perform on-line cleaning on the steam turbine. Each periodic speed-up and speed-down of the steam turbine realizes 1 cleaning, and at the same time, samples of the conductivity and silica content of the condensate in the condenser are taken for detection once an hour during cleaning. After cleaning 2 - 3 times, the cleaning is completed.

[0066] Specifically, (1) Steam turbine steam isolation: Before cleaning the steam turbine, stop the running steam turbine 2 and stop steam input. In this embodiment, the steam turbine 2 is used for the air separation unit, so the first isolation valve 110 and the second isolation valve 120 are completely closed, and at the same time, the couplings between the steam turbine 2 and the air compressor, and between the steam turbine 2 and the booster are all disengaged.

[0067] Meanwhile, fully close the first bypass valve 131, the second bypass valve 141, the first warm-up pipe vent valve 150 and the first drain valve 511 to cut off the steam entering the steam turbine 2 and prepare to cool down the steam turbine 2. Fully open the second warm-up pipe vent valve 160 and the second drain valve 521. The steam remaining in the main steam pipe 1 is discharged through the second warm-up pipe vent valve 160, which is also beneficial to relieve the pressure of the main steam pipe 1. At the same time, during the cooling process, part of the steam forms liquid phase water in the main steam pipe 1. Open the second drain valve 521, and drain the liquid phase water in the main steam pipe 1 through the post-isolation valve drain pipe 520. This process is beneficial to the cooling rate in the main steam pipe 1, enabling the steam turbine cylinder body to naturally cool down to below 80°C, and detecting the conductivity and silica content of the condensate in the condenser before cleaning.

[0068] Among them, close the shaft seal steam regulating valve of the steam turbine, the front and rear stop valves of the shaft seal steam regulating valve, and the bypass valve of the shaft seal steam regulating valve to prevent steam from leaking into the steam turbine 2 due to internal leakage of the valves.

[0069] Before cleaning, cool down the steam turbine cylinder body first to avoid the expansion of the cylinder and internal components of the steam turbine caused by high temperature, which increases the cleaning difficulty. And by reducing the cylinder temperature, it can avoid the low solubility of scale caused by too high temperature, and ensure the safety and effectiveness of the cleaning process.

[0070] (2) Steam warm-up: Adjust the second warm-up pipe vent valve 160 to an opening degree of 10 - 90%, adjust the second drain valve 521 to an opening degree of 10 - 90%, and adjust the third drain valve 531 to an opening degree of 10 - 50%.

[0071] Then adjust the first bypass valve 131 and the second bypass valve 141 to an opening degree of 10 - 50% to start warming up the main steam pipe 1 until the pressure value of the main pipe pressure sensor is 2.1 - 2.2 MPa and the temperature value of the remote temperature measurement point on the pipe wall is 220 - 230°C, and the warm-up ends. Mainly by adjusting the opening degrees of the first bypass valve 131 and the second bypass valve 141, control the amount of steam entering the main steam pipe 1 to warm up the main steam pipe 1, so that components such as the main steam pipe 1, various valves and flanges are evenly heated and expand slowly during the heating process to avoid excessive thermal stress caused by too rapid temperature change.

[0072] (3) Online cleaning: Start the steam turbine. By adjusting the opening degrees of the first bypass valve 131 and the second bypass valve 141, and the flow rate of the water spray cooling device 4, control the steam temperature in the main steam pipeline 1 to be 20 - 30°C overheated at the corresponding pressure. At the same time, perform periodic speed increase and decrease adjustment on the steam turbine for online cleaning. Each periodic speed increase and decrease of the steam turbine realizes 1 time of cleaning. At the same time, take samples and detect the conductivity and silica content of the condensate in the condenser once per hour. After cleaning 2 - 3 times, the cleaning ends. The silica content can be detected once per hour or two hours. Control the steam temperature in the main steam pipeline 1 to be 20 - 30°C overheated at the corresponding pressure to increase the liquid moisture in the steam, increase the solubility of the scale. At the same time, by performing periodic speed increase and decrease adjustment on the steam turbine, through the switching of the steam turbine speed, increase the contact between the steam turbine blades and the steam, and at the same time accelerate the scouring of the steam on the steam turbine, accelerate the dissolution and shedding of the scale, and thus improve the cleaning efficiency of the steam turbine 2.

[0073] Among them, during online cleaning, when it is necessary to repeat the cleaning after each periodic speed increase and decrease ends, it is necessary to repeat the operations in sequence from step (1) steam turbine steam isolation, steam pipe warming, and online cleaning. After the online cleaning is completely finished, when the temperature of the cylinder shell of the steam turbine 2 drops below 100°C, reinstall the couplings between the steam turbine and the air compressor, and between the steam turbine 2 and the supercharger.

[0074] Optionally, in the steam pipe warming step, the methods for adjusting the pressure and temperature in the main steam pipeline 1 include: when the pressure in the main steam pipeline 1 is less than 0.5 MPa, the heating rate is 5 - 10°C / min. When the temperature in the main steam pipeline 1 is greater than or equal to 150°C, open the cooling water regulating valve 410, increase the pressure at a rate of 0.1 - 0.3 MPa / min, and control the heating rate below 5°C / min until the pressure value of the main pipeline pressure sensor is 2.1 - 2.2 MPa and the temperature value of the remote temperature measuring point on the pipe wall is 220 - 230°C, and the pipe warming ends.

[0075] Specifically, through pipe warming, components such as the main steam pipeline 1, each valve, and flange are uniformly heated and slowly expanded during the heating process to avoid excessive thermal stress caused by too rapid temperature change. By starting pipe warming at a low pressure and then gradually increasing the pressure, it can ensure that no additional thermal stress occurs in the main steam pipeline 1 and each valve, thereby preventing component damage or deformation caused by excessive stress.

[0076] Optionally, in the online cleaning step, the process of periodic speed increase and decrease adjustment of the steam turbine includes: start the steam turbine, and control the steam turbine speed to be 500 rpm. After rotating for 2 - 5 minutes, increase the speed to 600 rpm and warm up for 30 - 40 minutes. Then increase the speed to 1100 rpm and warm up for 30 - 40 minutes. Finally, decrease the speed to 600 rpm, which is one periodic speed increase and decrease of the steam turbine.

[0077] Specifically, first control the steam turbine speed to 500 rpm. After rotating for 2 - 5 minutes, it shows that the steam turbine can rotate normally. Then increase the speed to 600 rpm for warm-up for 30 - 40 minutes. During the process of the speed reaching 600 rpm, check that there is no abnormal vibration in the system and the sound is normal. Then close the second warm pipe vent valve 160, the second drain valve 521, and the third drain valve 531 to maintain the stability and balance of the pressure and temperature in the main steam pipe 1. Increase the speed to 1100 rpm again, check the operating conditions of the steam turbine 2 and the main steam pipe 1, and check whether there is any abnormal vibration or sound to ensure the stable operation of the system. By adjusting the speed of the steam turbine 2 to increase and decrease, different impact forces are generated when the steam contacts the steam turbine blade rotor, thereby flushing the scale, improving the dissolution and shedding of the scale, and improving the cleaning efficiency.

[0078] Table 1 Comparison Table of Steam Pressure and Saturated Steam Temperature

[0079] Steam pressure (MPa) Saturated steam temperature (℃) 2.5 224 2.6 226 2.7 228 2.8 230 2.9 232 3.0 234 3.1 236 3.2 237 3.3 239 3.4 241 3.5 243 3.6 244 3.7 246 3.8 247 3.9 249 4.0 250

[0080] The following takes specific embodiments to illustrate the technical solutions of the present application in detail.

[0081] In the steam turbine online cleaning system of this embodiment, the operation process during specific work is as follows:

[0082] (1) Steam isolation of the steam turbine: Before cleaning the steam turbine, stop the running steam turbine 2 and stop the steam input. In this embodiment, since the steam turbine 2 is used for the air separation unit, the first isolation valve 110 and the second isolation valve 120 are fully closed. At the same time, all the couplings between the steam turbine 2 and the air compressor, and between the steam turbine 2 and the booster are disconnected.

[0083] At the same time, fully close the first bypass valve 131, the second bypass valve 141, the first warm pipe vent valve 150, and the first drain valve 511 to cut off the steam entering the steam turbine 2 and prepare to cool down the steam turbine 2. Fully open the second warm pipe vent valve 160 and the second drain valve 521. The steam remaining in the main steam pipe 1 is discharged through the second warm pipe vent valve 160, which is also beneficial for relieving the pressure of the main steam pipe 1. At the same time, open the second drain valve 521, and drain the liquid phase water in the main steam pipe 1 through the post-isolation valve drain pipe 520. This process is beneficial for the cooling rate in the main steam pipe 1. At the same time, close the shaft seal steam regulating valve of the steam turbine, the front and rear stop valves of the shaft seal steam regulating valve, and the bypass valve of the shaft seal steam regulating valve to prevent steam from leaking into the steam turbine 2 due to valve internal leakage. Confirm that the turning gear is in normal operation to make the steam turbine rotate slowly and be evenly heated. When the steam turbine cylinder body naturally cools down to below 80 °C, detect the conductivity and silica content of the condensate in the condenser 3 before cleaning.

[0084] (2) Steam pipe warming: Adjust the second pipe warming vent valve 160 to an opening degree of 10 - 90%, adjust the second drain valve 521 to an opening degree of 10 - 90%, and the third drain valve 531 to an opening degree of 10 - 50%.

[0085] Then adjust the first bypass valve 131 and the second bypass valve 141 to an opening degree of 10 - 50% to start warming the main steam pipe 1. The pressure and temperature adjustment methods in the main steam pipe 1 include: when the pressure in the main steam pipe 1 is less than 0.5 MPa, mainly control the steam volume entering the main steam pipe 1 by adjusting the opening degrees of the first bypass valve 131 and the second bypass valve 141, and control the heating rate at 5 - 10 °C / min. When the temperature in the main steam pipe 1 is greater than or equal to 150 °C, mainly adjust the opening degrees of the first bypass valve 131, the second bypass valve 141 and the cooling water regulating valve 410 to increase the pressure at a rate of 0.1 - 0.3 MPa / min, and control the heating rate below 5 °C / min. When the pressure value of the main pipe pressure sensor is 2.1 - 2.2 MPa and the temperature value of the wall remote temperature measuring point is 220 - 230 °C, the pipe warming ends.

[0086] (4) Online cleaning: Start the steam turbine, control the steam temperature in the main steam pipe 1 to be 20 - 30 °C overheated at the corresponding pressure by adjusting the opening degrees of the first bypass valve 131 and the second bypass valve 141 and the flow rate of the water spray cooling device 4 (as shown in Table 1). At the same time, perform periodic speed increase and decrease adjustment on the steam turbine for online cleaning. Each periodic speed increase and decrease of the steam turbine realizes 1 time of cleaning. At the same time, take samples and detect the conductivity content of the condensate in the condenser once per hour, and detect the silica content every two hours. After cleaning 2 - 3 times, the cleaning ends.

[0087] The process of periodic speed increase and decrease adjustment of the steam turbine includes: Start the steam turbine, first control the steam turbine speed at 500 rpm. After rotating for 2 - 5 minutes, it shows that the steam turbine can rotate normally. Then increase the speed to 600 rpm and warm the machine for 30 - 40 minutes. During the process of the speed of 600 rpm, check that there is no abnormal vibration in the system and the sound is normal, then close the second pipe warming vent valve 160, the second drain valve 521 and the third drain valve 531 to maintain the stability and balance of the pressure and temperature in the main steam pipe 1. Increase the speed to 1100 rpm again, check the operating conditions of the steam turbine 2 and the main steam pipe 1, and check whether there is any abnormal vibration or sound to ensure the stable operation of the system.

[0088] After the hot steam is cleaned in the steam turbine 2, it enters the condenser 3 through the exhaust port of the steam turbine 2 for condensation. Condensate is obtained in the condenser 3 and flows into the condensate collection tank 310 for collection. The water in the water spray cooling device 4 exchanges heat with the heat preservation removal section 170 and is collected in the spray water collection tank 171. Both the spray water and the condensate are transported to the water processor 6 for purification. First, solid impurities are removed through the filter screen filtering chamber 610, and then adsorption filtration is carried out through the activated carbon filtering chamber 620 to obtain purified water, which is recycled back to the water spray cooling device 4 through the circulating water pump 7.

[0089] Among them, during on-line cleaning, when it is necessary to repeat the cleaning after each periodic speed increase and decrease ends, it is necessary to repeat the operations in sequence from step (1): steam turbine steam isolation, steam warming, and on-line cleaning.

[0090] (4) After the on-line cleaning is completely finished, when the temperature of the cylinder shell of the steam turbine 2 drops below 100 °C, reinstall the couplings between the steam turbine and the air compressor, and between the steam turbine 2 and the supercharger. Start the negative pressure vacuum pump 750 to evacuate the heat preservation barrel 710 to make the vacuum degree in the heat preservation barrel 710 maintain 2 kPa.

[0091] In this embodiment, the steam turbine is cleaned three times, and the cleaning results are shown in Table 2

[0092] Table 2

[0093]

[0094] Note: The unit of conductivity is us / cm, and the unit of silicon dioxide is mg / L

[0095] It can be seen from Table 2 that both the conductivity and the SiO2 content first increase and then decrease, and the time consumed is short and the cleaning effect is good. When the conductivity ≤ 20 us / cm at the end of the third cleaning, the cleaning ends. The steam turbine is started and steam is introduced for use. During operation, the introduced steam will continue to displace the cleaning liquid in the steam turbine after the third cleaning, and the conductivity will decrease again. Therefore, when the conductivity ≤ 20 us / cm at the end of the third cleaning, the cleaning ends.

[0096] The comparison of the operating data of the steam turbine before and after cleaning is shown in Table 3

[0097] Table 3

[0098] Before cleaning After cleaning Steam turbine speed rpm 5900 5900 Main steam valve opening % 76.1 55.3 Shaft seal steam valve opening % 80.8 62.2 Chamber pressure MPa 3.1 2.2 Intermediate extraction steam pressure MPaA 1.285 1.143 Thrust bearing temperature ℃ 80.5 48.5 Axial displacement A mm -0.229 -0.018 Axial displacement B mm -0.229 -0.029 Air compressor guide vane opening % 48 85 Air compressor load % 81.6 94.3 Main steam pressure MPa 4.01 3.88 Oxygen load % 60 70.4

[0099] Observing Table 3, it is found that before cleaning, due to the scaling of the steam turbine, the pressure in the air separation unit wheel chamber and the intermediate extraction pressure are high. In order to maintain the operation of the air separation unit by reducing the load of the air compressor as much as possible, three screw air compressors are required for air supplementation. The guide vanes of the air compressor have been closed to the minimum, the axial displacement is high, and the temperature of the thrust bearing of the steam turbine has risen to 106 °C at most, basically reaching the operation limit.

[0100] After cleaning, the parameters of the steam turbine basically return to the parameters before fouling. The air compressor can be loaded to full load operation. The opening of the main steam valve is only 55%, the axial displacement is normal, and the temperature of the thrust bearing is normal. There is basically no need to start the screw air compressor to supplement air. After cleaning, the influence caused by the fouling of the steam turbine can hardly be observed. It is estimated that at least more than 90% of the fouling of the steam turbine has been removed this time.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An on-line cleaning system for a steam turbine, characterized in that, Including: The main steam pipeline (1), steam turbine (2), condenser (3) and spray cooling device (4); The outlet end of the main steam pipeline (1) is communicated with the steam inlet of the steam turbine (2), and the exhaust port of the steam turbine (2) is communicated with the steam inlet of the condenser (3); A first isolation valve (110) and a second isolation valve (120) are sequentially arranged on the main steam pipeline (1) near the steam inlet end along the steam flow direction. A first bypass pipeline (130) is arranged in parallel with the first isolation valve (110), and a first bypass valve (131) is arranged on the first bypass pipeline (130). A second bypass pipeline (140) is arranged in parallel with the second isolation valve (120), and a second bypass valve (141) is arranged on the second bypass pipeline (140); A first warm-up drain valve (150) is arranged on the main steam pipeline (1) in front of the first isolation valve (110), and a second warm-up drain valve (160) is arranged on the main steam pipeline (1) between the second isolation valve (120) and the steam turbine (2); An insulation removal section (170) is arranged on the main steam pipeline (1) between the second isolation valve (120) and the second warm-up drain valve (160). The water spray port of the spray cooling device (4) is located directly above the insulation removal section (170). A remote wall temperature measurement point (180) and a main pipeline pressure sensor (190) are arranged on the main steam pipeline (1) after the insulation removal section (170); 2. The steam turbine online cleaning system according to claim 1, characterized in that, A plurality of drain pipes are further arranged on the main steam pipeline (1), including: an isolation valve intermediate drain pipe (510) between the first isolation valve (110) and the second isolation valve (120). A first drain valve (511) is arranged on the isolation valve intermediate drain pipe (510). A drain pipe behind the isolation valve (520) is arranged between the second isolation valve (120) and the insulation removal section (170). A second drain valve (521) is arranged on the drain pipe behind the isolation valve (520). A third drain pipe (530) is arranged between the remote wall temperature measurement point (180) and the steam turbine (2). A third drain valve (531) is arranged on the third drain pipe (530); 3. The on-line cleaning system for steam turbines according to claim 1, characterized in that, The length of the insulation removal section (170) is 15 - 20 m.

4. The on-line cleaning system for steam turbines according to claim 1, characterized in that, The cleaning system further includes a water circulation device. The water circulation device includes a spray water collection tank (171), a condensate collection tank (310), a water processor (6) and a circulation water pump (7). The spray water collection tank (171) is located below the insulation removal section (170). The inlet of the condensate collection tank (310) is communicated with the outlet of the condenser (3). The water outlets of the spray water collection tank (171) and the condensate collection tank (310) are both communicated with the water processor (6). A circulation water pump (7) is connected between the purified water outlet of the water processor (6) and the water inlet of the spray cooling device (4).

5. The on-line cleaning system for steam turbines according to claim 4, characterized in that, The water processor (6) includes a filter screen filtering chamber (610), an activated carbon filtering chamber (620), and a purified water chamber (630) connected in sequence; The water outlets of the spray water collection tank (171) and the condensate water collection tank (310) are both communicated with the filter screen filtering chamber (610), and the outlet of the purified water chamber (630) is communicated with the water inlet of the water spraying and cooling device (4).

6. The on-line cleaning system for steam turbines according to claim 5, characterized in that, A heat preservation barrel (710) is sleeved on the outer periphery of the heat preservation removal section (170). A cooling water inlet (720) and a cooling water outlet (730) are respectively arranged at both ends of the heat preservation barrel (710). A cooling water regulating valve (410) is connected between the cooling water inlet (720) and the outlet of the water spraying and cooling device (4), and the cooling water outlet (730) is connected with the inlet of the spray water collection tank (171).

7. The on-line cleaning system for steam turbines according to claim 6, characterized in that, A heat preservation barrel pressure sensor (740) is arranged in the heat preservation barrel (710), and the heat preservation barrel (710) is further connected with a negative pressure vacuum pump (750).

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