A medium-pressure industrial steam desuperheating and pressure reduction device and method

Abstract

This invention relates to a medium-pressure industrial steam desuperheating and pressure reduction device and method, belonging to the field of steam desuperheating and pressure reduction technology. Its main pipeline includes a mixing pipeline section with an internal Venturi tube located in its middle. A pressure reducing valve is installed near the steam inlet of the main pipeline. The throat length of the Venturi tube is not less than 1200 mm, and several sets of nozzles are installed in the throat. The distance between the last nozzle set and the end of the Venturi tube throat is not less than 700 mm, and it is connected to a primary bypass pipeline. The primary bypass pipeline is connected to a desuperheating water pipeline. Each remaining nozzle set is connected to a secondary bypass pipeline, which is connected to the desuperheating water pipeline through a corresponding electrically operated shut-off valve. The desuperheating water pipeline is equipped with a regulating valve group and a desuperheating water flow meter. In this invention, the control system controls the opening and closing of the electrically operated shut-off valves of different nozzle sets according to the flow rate of the desuperheating water flow meter, so that the total flow rate of the operating nozzle sets matches the current flow rate of the desuperheating water pipeline, maintaining a stable steam outlet temperature.

Description

Technical Field

[0001] This invention relates to the field of steam desuperheating and pressure reduction technology, specifically to a medium-pressure industrial steam desuperheating and pressure reduction device and method. Background Technology

[0002] In industrial steam supply systems, desuperheating and pressure-reducing devices are core equipment used to reduce the high pressure and temperature of steam upstream to the stable parameters required by downstream users. Traditional desuperheating and pressure-reducing devices, especially Venturi desuperheaters, work by utilizing the throttling effect of the Venturi tube to generate a high-speed zone and turbulence at the throat, atomizing the injected desuperheating water and mixing it with the superheated steam, thereby achieving cooling.

[0003] In actual operation, the pressure, temperature or flow rate of the upstream inlet steam often fluctuates significantly due to changes in user demand or adjustments in the load of the upstream unit. In order to maintain the stability of the outlet steam temperature, the flow rate of the desuperheating water needs to be adjusted accordingly and quickly.

[0004] However, existing Venturi-type desuperheating and depressurization devices typically use a fixed number of nozzles. When the required desuperheating water flow rate is too small, the pressure difference before and after the nozzles decreases significantly, leading to poor atomization of the desuperheating water and the formation of large-diameter water droplets, which affects heat exchange efficiency. When the required desuperheating water flow rate is too large, the number of nozzles is relatively insufficient, causing the nozzles to work under overload, affecting atomization effect and service life. Both situations can lead to fluctuations in the outlet steam temperature. Furthermore, in existing technologies, the length from the last spray point to the desuperheater outlet is often too short. Under conditions of poor atomization or large flow fluctuations, some water droplets often fail to completely vaporize before reaching the outlet, which may cause water hammer in downstream equipment, affecting the desuperheating effect. Summary of the Invention

[0005] To address the technical problem that existing Venturi-type desuperheating and pressure reducing devices typically use a fixed number of nozzles, and the length from the last spray point to the desuperheater outlet is often too short, resulting in weak adaptability to changes in operating conditions and an inability to guarantee the desuperheating effect when the pressure and temperature of the inlet steam and the flow rate change significantly, this invention provides a medium-pressure industrial steam desuperheating and pressure reducing device and method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A medium-pressure industrial steam desuperheating and pressure reducing device includes a main pipeline with a steam inlet at one end and a steam outlet at the other. The main pipeline includes a mixing pipe section located in its middle. A pressure reducing valve is installed near the steam inlet, with its rear end connected to the mixing pipe section. A Venturi tube is installed within the mixing pipe section, with a throat length of at least 1200 mm. Several sets of nozzles are installed at the throat of the Venturi tube, with the distance between the last set of nozzles and the end of the throat of the Venturi tube at least 700 mm. The last set of nozzles is connected to a primary bypass pipe. The nozzle group is connected to the front end of the desuperheating water pipe, and each remaining nozzle group is connected to the secondary bypass pipe. Each secondary bypass pipe is connected to the front end of the desuperheating water pipe through a corresponding electric shut-off valve. The rear end of the desuperheating water pipe is the desuperheating water inlet. The desuperheating water pipe is equipped with a regulating valve group and a desuperheating water flow meter. The desuperheating water flow meter is located at the rear end of the regulating valve group. The pressure reducing valve, electric shut-off valve, regulating valve group, and desuperheating water flow meter are all electrically connected to the control system. The control system controls the opening or closing of the electric shut-off valves of different nozzle groups according to the flow rate of the desuperheating water flow meter, so that the total flow rate of the operating nozzle group matches the current flow rate of the desuperheating water pipe.

[0007] This invention features several nozzle groups. The control system automatically controls the opening and closing of the electric shut-off valves corresponding to different nozzle groups based on the actual flow rate measured by the desuperheating water flow meter, ensuring that the total flow rate of the operating nozzle groups matches the current flow rate of the desuperheating water pipe. When the desuperheating water flow rate is low, only some nozzle groups are opened to maintain the pressure difference before and after the nozzles and improve the atomization effect. When the desuperheating water flow rate is high, more nozzle groups are opened to avoid overloading the nozzles, thus ensuring the stability of the desuperheating effect even when the inlet steam parameters and flow rate fluctuate significantly. The throat length of the Venturi tube in this invention is no less than 1200 mm, and the distance between the last nozzle group and the throat end of the Venturi tube is no less than 700 mm. This extends the time for the atomized water droplets and steam to undergo high-speed turbulent flow within the Venturi tube, ensuring thorough mixing and providing sufficient space and distance for water droplet vaporization. This prevents incompletely vaporized water droplets from entering downstream pipes, avoiding water hammer in downstream equipment, ensuring safe system operation, improving heat exchange efficiency, and guaranteeing the desuperheating effect.

[0008] As a further improvement to a medium-pressure industrial steam desuperheating and pressure reducing device, each nozzle group includes two nozzle bodies. The spray direction of both nozzle bodies is set towards the center of the radial section of the mixing pipe segment, and the spray directions of the two nozzle bodies in each nozzle group are opposite to each other. This causes the desuperheating water sprayed from the two nozzle bodies to collide and impact in the central area of ​​the pipe, further breaking the desuperheating water into smaller droplets, significantly improving the atomization effect, increasing the contact area between the desuperheating water and the steam, improving the heat exchange efficiency, and making the outlet steam temperature more uniform and stable.

[0009] As a further improvement to a medium-pressure industrial steam desuperheating and pressure-reducing device, the nozzle group consists of three sets: a first nozzle group, a second nozzle group, and a third nozzle group. The nozzle bodies of the first and second nozzle groups are located on the same radial cross-section of the mixing pipe section, while the third nozzle group is located at the rear end of the first and second nozzle groups. The spray direction of the nozzle bodies in the first and second nozzle groups is inclined at 45°, while the spray direction of the two nozzle bodies in the third nozzle group is horizontal. When the first and second nozzle groups need to be activated, the desuperheating water flow rate increases. By setting the first and second nozzle groups on the same radial cross-section and tilting their spray directions at 45°, a multi-angle, multi-layered atomized water spray structure is formed with the normally open third nozzle group. When both the first and second nozzle bodies are activated, the atomized water droplets generated by the first and second nozzle groups form a swirling mixture with the steam, prolonging the suspension time of the water droplets in the steam, improving heat exchange efficiency, and ensuring the desuperheating effect.

[0010] As a further improvement to a medium-pressure industrial steam desuperheating and pressure-reducing device, when the control system detects that the flow rate of the desuperheating water pipe is greater than 8 T / H, the control system opens the electric shut-off valve corresponding to the first group of nozzles; when the flow rate of the desuperheating water pipe is greater than 20 T / H, the electric shut-off valve corresponding to the second group of nozzles opens; when the flow rate of the desuperheating water pipe is less than 18 T / H, the electric shut-off valve corresponding to the second group of nozzles closes; and when the flow rate of the desuperheating water pipe is less than 7 T / H, the electric shut-off valve corresponding to the first group of nozzles closes. By matching the appropriate number of nozzle groups according to different flow ranges, automated stepped switching of the nozzle groups is achieved, ensuring that a sufficient pressure difference is maintained before and after the nozzles under various loads, guaranteeing atomization effect, and thus ensuring the stability of the outlet steam temperature. In addition, reasonable hysteresis intervals are set between the opening and closing thresholds of the electric shut-off valves corresponding to the first and second nozzle groups. For example, there is a hysteresis interval of 1T / H between the opening threshold of 8T / H and the closing threshold of 7T / H for the first nozzle group, and a hysteresis interval of 2T / H between the opening threshold of 20T / H and the closing threshold of 18T / H for the second nozzle group. This can effectively prevent the electric shut-off valve from frequently starting and stopping near the flow boundary, avoid motor overheating protection, and extend the service life of the electric shut-off valve.

[0011] As a further improvement to the medium-pressure industrial steam desuperheating and pressure reducing device, an electric gate valve is installed near the steam inlet on the main pipeline. Electric gate valve one is located upstream of the pressure reducing valve, and electric gate valves two are connected externally to both sides of the pressure reducing valve. Electric gate valve one and electric gate valve two are electrically connected to the control system. Electric gate valve two serves as a bypass channel for the pressure reducing valve. In the event of a pressure reducing valve failure or when bypass operation is required, electric gate valve two can be opened, allowing steam to bypass the pressure reducing valve and directly enter the mixing pipeline section. This avoids steam supply interruption due to pressure reducing valve failure and improves system reliability.

[0012] As a further improvement to a medium-pressure industrial steam desuperheating and pressure-reducing device, the mixing pipeline section includes an evaporation pipeline located downstream of the venturi tube. The evaporation pipeline is at least 5 meters long and is equipped with an electric gate valve III and an orifice flow meter. The orifice flow meter is located downstream of the electric gate valve III, and both are electrically connected to the control system. The control system regulates the flow of the regulating valve group based on the flow rate measured by the orifice flow meter. The minimum length of the evaporation pipeline (at least 5 meters) provides sufficient evaporation distance and time for atomized water droplets, ensuring complete vaporization before the droplets enter the downstream pipeline and preventing erosion damage to downstream equipment from the two-phase flow. The control system precisely controls the amount of desuperheating water injected into the regulating valve group based on the steam flow rate measured by the orifice flow meter, forming a closed-loop control system. This ensures that the outlet steam temperature remains within the set range, avoiding problems of excessive or insufficient water injection.

[0013] As a further improvement to a medium-pressure industrial steam desuperheating and pressure-reducing device, the regulating valve assembly is a skid-mounted unit. The assembly includes, from front to back, an electrically operated isolation valve I, an electrically operated regulating valve, and an electrically operated isolation valve II. Check valves are externally connected to both sides of the electrically operated regulating valve. The electrically operated regulating valve and the check valves are electrically connected to the control system. The skid-mounted design integrates the electrically operated isolation valve I, the electrically operated regulating valve, the electrically operated isolation valve II, and the check valves into a single unit. On-site installation only requires connecting the inlet and outlet pipes, significantly shortening the construction period, reducing installation costs, and facilitating maintenance. Electrically operated isolation valves I and II are located before and after the electrically operated regulating valve, respectively, enabling double isolation during maintenance of the regulating valve. The check valves prevent backflow of the desuperheating water, ensuring system safety.

[0014] As a further improvement to a medium-pressure industrial steam desuperheating and pressure-reducing device, a full-opening safety valve is installed at the front end of the electric gate valve three. This full-opening safety valve is located at the rear end of the nozzle assembly, and a condensate drain device is installed on the pipeline between the full-opening safety valve and the electric gate valve three. The full-opening safety valve, located at the rear end of the nozzle assembly, rapidly opens to release pressure when the outlet steam pressure of the desuperheating and pressure-reducing device exceeds the set value, preventing damage to downstream equipment and pipelines due to overpressure and ensuring system safety. The condensate drain device, installed on the pipeline between the full-opening safety valve and the electric gate valve three, automatically drains accumulated condensate from the pipeline, preventing water hammer and avoiding corrosion and erosion of the full-opening safety valve and downstream equipment by accumulated water.

[0015] As a further improvement to a medium-pressure industrial steam desuperheating and pressure reducing device, the main pipeline near the steam outlet is equipped with pressure gauges, thermometers with sleeves, pressure transmitter 1, integrated temperature transmitter 1 with a sleeve, pressure transmitter 2, integrated temperature transmitter 2 with a sleeve, pressure transmitter 3, and integrated temperature transmitter 3 with a spacing of 300mm or more. All three sets of pressure transmitters and integrated temperature transmitters with sleeves are electrically connected to the control system. The installation of three sets of pressure transmitters and integrated temperature transmitters with sleeves at the steam outlet achieves triple redundancy measurement of key parameters, preventing erroneous operation due to a single instrument failure and improving system reliability. Furthermore, the multiple sets of pressure transmitters and integrated temperature transmitters with sleeves can cross-calibrate, providing the control system with more accurate outlet steam parameter information, which helps to achieve more precise desuperheating water regulation. Setting a spacing of 300mm or more facilitates installation, maintenance, and reading.

[0016] The technical solution adopted in the medium-pressure industrial steam desuperheating and depressurization method of this invention is as follows: A method for desuperheating and depressurizing medium-pressure industrial steam, applicable to any of the medium-pressure industrial steam desuperheating and depressurization devices described above, includes the following steps: The actual flow rate of desuperheating water is monitored in real time by a desuperheating water flow meter installed on the desuperheating water pipe; The flow range is determined based on the actual flow rate of the desuperheating water input. Based on the judgment results, control the opening or closing of different groups of electric shut-off valves to match the total flow rate of the operating nozzle group with the current flow rate of the desuperheating water pipe.

[0017] This invention directly uses the desuperheating water flow rate as the criterion for determining the number of nozzle groups to switch. Compared to using steam flow rate or outlet temperature as the criterion, the response is more direct and rapid, and it can adapt to changes in the desuperheating water flow rate in a timely manner, avoiding outlet temperature fluctuations caused by control lag. This invention can be applied to desuperheating and pressure reducing devices of different capacity levels; it only requires adjusting the threshold of the flow range according to the actual operating conditions, and has good versatility and scalability.

[0018] The beneficial effects of this invention include: This invention incorporates several nozzle groups. The control system automatically controls the opening or closing of the electric shut-off valves corresponding to different nozzle groups based on the actual flow rate measured by the desuperheating water flow meter, ensuring that the total flow rate of the operating nozzle groups matches the current flow rate of the desuperheating water pipe. When the desuperheating water flow rate is low, only some nozzle groups are opened to maintain the pressure difference before and after the nozzles and improve the atomization effect. When the desuperheating water flow rate is high, more nozzle groups are opened to prevent the nozzles from overloading, thus ensuring the stability of the desuperheating effect even when the inlet steam parameters and flow rate fluctuate significantly.

[0019] The throat length of the Venturi tube in this invention is not less than 1200mm, and the distance between the last set of nozzles and the end of the throat of the Venturi tube is not less than 700mm. This prolongs the time for atomized water droplets and steam to flow at high speed in the Venturi tube, ensuring that the two are fully mixed. It provides sufficient space and distance for water droplet vaporization, prevents incompletely vaporized water droplets from entering downstream pipes, avoids water hammer in downstream equipment, ensures safe system operation, improves heat exchange efficiency, and guarantees the cooling effect.

[0020] This invention can be applied to de-cooling and pressure reducing devices of different capacity levels. It only requires adjusting the threshold of the flow range according to the actual working conditions, and has good versatility and scalability. Attached Figure Description

[0021] To more clearly illustrate the technical solution of this patent, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this patent. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the pipeline structure of a medium-pressure industrial steam desuperheating and pressure reducing device according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the first nozzle group and the second nozzle group in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the third nozzle group in a specific embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Main pipeline; 2. Steam inlet; 3. Steam outlet; 4. Mixed pipeline section; 5. Pressure reducing valve; 6. Primary bypass pipeline; 7. Cooling water pipes; 8. Secondary bypass pipeline; 9. Electric shut-off valve; 10. Desuperheating water inlet; 11. Control valve assembly; 12. Desuperheating water flow meter; 13. Control system; 14. Nozzle body; 15. First nozzle group; 16. Second nozzle group; 17. Third nozzle group; 18. Electric gate valve; 19. Electric gate valve II; 20. Electric gate valve (Type III); 21. Orifice plate flow meter; 22. One electric isolation valve; 23. Electric regulating valve; 24. Electric isolation valve II; 25. Check valve; 26. Full-opening safety valve; 27. Drainage device; 28. Pressure gauge; 29. Thermometer with sleeve; 30. Pressure transmitter 1; 31. Integrated temperature transmitter with sleeve; 32. Pressure transmitter II; 33. Integrated temperature transmitter with sleeve (II); 34. Pressure transmitter three; 35. Integrated temperature transmitter with sleeve (III). Detailed Implementation

[0024] To make the objectives, features, and advantages of this patent more apparent and understandable, the technical solutions of this patent will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this patent, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0025] Reference Figure 1This embodiment proposes a medium-pressure industrial steam desuperheating and pressure reducing device, including a main pipeline 1. The main pipeline 1 has a steam inlet 2 at its front end and a steam outlet 3 at its rear end. The main pipeline 1 includes a mixing pipeline section 4 located in its middle. Near the steam inlet 2, the main pipeline 1 is equipped with an electric gate valve 18 and a pressure reducing valve 5 from front to back. Electric gate valves 19 are externally connected to both sides of the pressure reducing valve 5. The rear end of the pressure reducing valve 5 is connected to the mixing pipeline section 4. A venturi tube is installed inside the mixing pipeline section 4, and the throat length of the venturi tube is not less than 1200 mm. Figure 2 and Figure 3 The throat of the venturi tube is provided with three sets of nozzles: a first nozzle set 15, a second nozzle set 16, and a third nozzle set 17. Each nozzle set includes two nozzle bodies 14, with the spray direction of both nozzle bodies 14 facing the center of the radial section of the mixing pipe section 4. The spray directions of the two nozzle bodies 14 in each nozzle set are opposite to each other. The nozzle bodies 14 of the first nozzle set 15 and the second nozzle set 16 are located on the same radial section of the mixing pipe section 4. The third nozzle set 17 is located at the rear end of the first nozzle set 15 and the second nozzle set 16. The spray direction of the nozzle bodies 14 in the first nozzle set 15 and the second nozzle set 16 is inclined at 45°, while the spray direction of the two nozzle bodies 14 in the third nozzle set 17 is horizontal. The distance between the third nozzle set 17 and the end of the throat of the venturi tube is not less than 700 mm. The third nozzle group 17 is connected to the primary bypass pipe 6, which is connected to the front end of the desuperheating water pipe 7. The third nozzle group 17 is normally open. The first nozzle group 15 and the second nozzle group 16 are both connected to their corresponding secondary bypass pipes 8. Each secondary bypass pipe 8 is connected to the front end of the desuperheating water pipe 7 through a corresponding electric shut-off valve 9. The rear end of the desuperheating water pipe 7 is the desuperheating water inlet 10. The desuperheating water pipe 7 is equipped with a regulating valve group 11 and a desuperheating water flow meter 12, with the flow meter 12 located at the rear end of the regulating valve group 11.

[0026] Pressure reducing valve 5, electric shut-off valve 9, regulating valve group 11, and desuperheating water flow meter 12 are all electrically connected to control system 13. Electric gate valve one 18 and electric gate valve two 19 are also electrically connected to control system 13. When control system 13 detects that the flow rate of desuperheating water pipe 7 is greater than 8T / H, control system 13 controls the opening of electric shut-off valve 9 corresponding to the first group of nozzles, with a flow rate applicable range of 8-20T / H; when the flow rate of desuperheating water pipe 7 is greater than 20T / H, it opens electric shut-off valve 9 corresponding to the second group of nozzles, with a flow rate applicable range of 15-36T / H; when the flow rate of desuperheating water pipe 7 is less than 18T / H, it closes electric shut-off valve 9 corresponding to the second group of nozzles, with a flow rate applicable range of 8-18T / H; when the flow rate of desuperheating water pipe 7 is less than 7T / H, it closes electric shut-off valve 9 corresponding to the first group of nozzles, with a flow rate applicable range of 3-6T / H. Therefore, the control system 13 can control the opening or closing of the electric shut-off valve 9 of different nozzle groups according to the flow rate of the desuperheating water flow meter 12, so that the total flow rate of the operating nozzle group matches the current flow rate of the desuperheating water pipe 7.

[0027] In this embodiment, all six nozzle bodies 14 can be spring-back pressure nozzles, the first nozzle group 15 and the second nozzle group 16 can be nozzles with a water spray volume of 3.5-7T / H, and the third nozzle group 17 can be nozzles with a water spray volume of 1.5-3T / H.

[0028] The mixing pipeline section 4 includes an evaporation pipeline located at the rear end of the venturi tube. The length of the evaporation pipeline is not less than 5 meters. An electric gate valve 20 and an orifice flow meter 21 are installed on the evaporation pipeline. The orifice flow meter 21 is located at the rear end of the electric gate valve 20. The electric gate valve 20 and the orifice flow meter 21 are electrically connected to the control system 13. The control system 13 controls the flow regulation of the regulating valve group 11 based on the flow rate of the orifice flow meter 21. A full-opening safety valve 26 is installed at the front end of the electric gate valve 20. The full-opening safety valve 26 is located at the rear end of the nozzle group. A drain device 27 is installed on the pipeline between the full-opening safety valve 26 and the electric gate valve 20.

[0029] The regulating valve group 11 is a skid-mounted device. The regulating valve group 11 includes an electric isolation valve 22, an electric regulating valve 23 and an electric isolation valve 24 distributed sequentially from the front end to the rear. Check valves 25 are externally connected to both sides of the electric regulating valve 23. The electric regulating valve 23 and the check valve 25 are electrically connected to the control system 13 respectively.

[0030] Near the steam outlet 3 on the main pipeline 1, pressure gauges 28, thermometers with sleeves, pressure transmitter 30, integrated temperature transmitter with sleeves 31, pressure transmitter 22, integrated temperature transmitter with sleeves 33, pressure transmitter 34, and integrated temperature transmitter with sleeves 35 are distributed sequentially from the front end to the rear end with a spacing of 300 mm or more. All of these components are electrically connected to the control system 13.

[0031] In this embodiment, three industrial gas supply pipes are connected to the steam outlet 3 of the main pipeline 1.

[0032] The inlet steam parameters in this embodiment are: design pressure 7 MPa.g, design temperature 547℃, working pressure 1.8-5.5 MPa.a, and working temperature 450-540℃.

[0033] In this embodiment, the outlet steam parameters are: design pressure 2.7 MPa.g, design temperature 380℃, working pressure 2.2 MPa.a, and working temperature 320℃.

[0034] In this embodiment, the desuperheating water is designed to have a pressure of 10 MPa, an operating pressure of 5.6 MPa, and a design temperature of 50°C.

[0035] This embodiment also proposes a method for desuperheating and depressurizing medium-pressure industrial steam, applicable to the aforementioned medium-pressure industrial steam desuperheating and depressurization device, comprising the following steps: The actual flow rate of desuperheating water is monitored in real time by a desuperheating water flow meter 12 installed on the desuperheating water pipe 7. The flow range is determined based on the actual flow rate of the desuperheating water input. Based on the judgment result, control the opening or closing of the electric shut-off valves 9 of different groups to match the total flow rate of the nozzle group in operation with the current flow rate of the desuperheating water pipe 7.

[0036] The above description of the disclosed embodiments enables those skilled in the art to implement or use this patent. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this patent. Therefore, this patent is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A medium-pressure industrial steam desuperheating and pressure reducing device, comprising a main pipeline (1), characterized in that, The main pipeline (1) has a steam inlet (2) at the front end and a steam outlet (3) at the rear end. The main pipeline (1) includes a mixing pipeline section (4) located in the middle. A pressure reducing valve (5) is provided near the steam inlet (2) of the main pipeline (1). The rear end of the pressure reducing valve (5) is connected to the mixing pipeline section (4). A venturi tube is provided in the mixing pipeline section (4). The throat length of the venturi tube is not less than 1200 mm. Several sets of nozzles are provided at the throat of the venturi tube. The distance between the last set of nozzles and the end of the throat of the venturi tube is not less than 700 mm. The last set of nozzles is connected to the first-level bypass pipeline (6). The first-level bypass pipeline (6) is connected to the front end of the desuperheating water pipe (7). Each remaining set of nozzles is connected to the second-level bypass. Pipeline (8) is connected, and each secondary bypass pipeline (8) is connected to the front end of the desuperheating water pipe (7) through the corresponding electric shut-off valve (9). The rear end of the desuperheating water pipe (7) is the desuperheating water inlet (10). The desuperheating water pipe (7) is equipped with a regulating valve group (11) and a desuperheating water flow meter (12). The desuperheating water flow meter (12) is located at the rear end of the regulating valve group (11). The pressure reducing valve (5), electric shut-off valve (9), regulating valve group (11), and desuperheating water flow meter (12) are all electrically connected to the control system (13). The control system (13) controls the opening or closing of the electric shut-off valve (9) of different nozzle groups according to the flow rate of the desuperheating water flow meter (12), so that the total flow rate of the operating nozzle group matches the current flow rate of the desuperheating water pipe (7).

2. The medium-pressure industrial steam desuperheating and pressure reducing device according to claim 1, characterized in that, Each nozzle group includes two nozzle bodies (14), and the spraying direction of the two nozzle bodies (14) is set towards the center of the radial section of the mixing pipe section (4). The spraying directions of the two nozzle bodies (14) in each nozzle group are set opposite to each other.

3. The medium-pressure industrial steam desuperheating and pressure reducing device according to claim 2, characterized in that, There are three nozzle groups: the first nozzle group (15), the second nozzle group (16), and the third nozzle group (17). The nozzle bodies (14) of the first nozzle group (15) and the second nozzle group (16) are located on the same radial section of the mixing pipe section (4). The third nozzle group (17) is located at the rear end of the first nozzle group (15) and the second nozzle group (16). The spray direction of the nozzle bodies (14) in the first nozzle group (15) and the second nozzle group (16) is set at an angle of 45°. The spray direction of the two nozzle bodies (14) in the third nozzle group (17) is set horizontally.

4. The medium-pressure industrial steam desuperheating and depressurization device according to claim 3, characterized in that, When the control system (13) detects that the flow rate of the desuperheating water pipe (7) is greater than 8T / H, the control system (13) controls the opening of the electric shut-off valve (9) corresponding to the first group of nozzles; when the flow rate of the desuperheating water pipe (7) is greater than 20T / H, the electric shut-off valve (9) corresponding to the second group of nozzles is opened; when the flow rate of the desuperheating water pipe (7) is less than 18T / H, the electric shut-off valve (9) corresponding to the second group of nozzles is closed; when the flow rate of the desuperheating water pipe (7) is less than 7T / H, the electric shut-off valve (9) corresponding to the first group of nozzles is closed.

5. The medium-pressure industrial steam desuperheating and pressure reducing device according to claim 1, characterized in that, Electric gate valve 1 (18) is installed near the steam inlet (2) of the main pipeline (1). Electric gate valve 1 (18) is located at the front end of the pressure reducing valve (5). Electric gate valve 2 (19) is connected to both sides of the pressure reducing valve (5). Electric gate valve 1 (18) and electric gate valve 2 (19) are electrically connected to the control system (13) respectively.

6. The medium-pressure industrial steam desuperheating and pressure reducing device according to claim 1, characterized in that, The mixed pipeline section (4) includes an evaporation pipeline located at the rear end of the venturi tube. The length of the evaporation pipeline is not less than 5 meters. An electric gate valve (20) and an orifice flow meter (21) are installed on the evaporation pipeline. The orifice flow meter (21) is located at the rear end of the electric gate valve (20). The electric gate valve (20) and the orifice flow meter (21) are electrically connected to the control system (13). The control system (13) controls the flow regulation of the regulating valve group (11) according to the flow of the orifice flow meter (21).

7. The medium-pressure industrial steam desuperheating and pressure reducing device according to claim 1, characterized in that, The regulating valve group (11) is a skid-mounted device. The regulating valve group (11) includes an electric isolation valve one (22), an electric regulating valve (23) and an electric isolation valve two (24) distributed from front to back. Check valves (25) are connected to both sides of the electric regulating valve (23). The electric regulating valve (23) and the check valve (25) are electrically connected to the control system (13).

8. A medium-pressure industrial steam desuperheating and pressure reducing device according to claim 6, characterized in that, The front end of the electric gate valve three (20) is equipped with a full-lift safety valve (26), which is located at the rear end of the nozzle assembly. A drain device (27) is provided on the pipeline between the full-lift safety valve (26) and the electric gate valve three (20).

9. A medium-pressure industrial steam desuperheating and pressure reducing device according to claim 1, characterized in that, The main pipeline (1) near the steam outlet (3) is arranged from front to back with pressure gauges (28), thermometers with sleeves (29), pressure transmitter one (30), integrated temperature transmitter one (31), pressure transmitter two (32), integrated temperature transmitter two (33), pressure transmitter three (34) and integrated temperature transmitter three (35) with a spacing of greater than or equal to 300 mm. Pressure transmitter one (30), integrated temperature transmitter one (31), pressure transmitter two (32), integrated temperature transmitter two (33), pressure transmitter three (34) and integrated temperature transmitter three (35) are all electrically connected to the control system (13).

10. A method for desuperheating and depressurizing medium-pressure industrial steam, characterized in that, An application to a medium-pressure industrial steam desuperheating and pressure reducing device as described in any one of claims 1-9, comprising the following steps: The actual desuperheating water flow rate is monitored in real time by a desuperheating water flow meter (12) installed on the desuperheating water pipe (7); The flow range is determined based on the actual flow rate of the desuperheating water input. Based on the judgment result, control the opening or closing of the electric shut-off valves (9) of different groups to match the total flow rate of the nozzle group in operation with the current flow rate of the desuperheating water pipe (7).

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