Industrial steam extraction capacity increasing transformation method based on optimized steam turbine

Abstract

The invention discloses an industrial steam extraction capacity increasing transformation method based on steam turbine optimization. According to the invention, by integrating the high and low bypass systems and optimizing the steam extraction structure, the steam supply flexibility and the energy utilization efficiency are obviously improved. Through a high-low side combined steam supply mode, the system can dynamically distribute the supply proportion of 1.2 MPa and 0.6 MPa industrial extraction steam, so that the multi-pressure-grade steam utilization requirement of an industrial park is met, and the priority of heating and heat supply in winter can be considered. After transformation, a single unit can independently undertake steam extraction tasks of different pressure grades, and the two units are standby for each other, so that the reliability and continuity of the steam supply system are greatly enhanced. Meanwhile, due to pipeline design and optimal configuration of temperature and pressure reduction equipment, energy loss in the steam conveying process is reduced, the service life of the equipment is prolonged through strict checking of materials and the flow speed, the operation and maintenance cost is reduced, and efficient balance of combined heat and power generation is achieved through a cooperative control strategy. And in winter, the heating heat supply amount is preferentially guaranteed, and the power supply coal consumption is remarkably reduced through switching of the high back pressure technology and the low-pressure cylinder zero output technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial steam turbines, and specifically relates to an industrial extraction steam capacity increase and transformation method based on optimizing steam turbines. Background Art

[0002] Industrial extraction steam capacity increase and transformation refers to a transformation project that upgrades the steam boilers and their auxiliary systems in industrial enterprises to improve steam production and efficiency. This transformation usually includes technical measures such as increasing the boiler heating surface area, optimizing the combustion system, improving the extraction equipment, and enhancing the control system, aiming to meet the growing steam demand of enterprises, while reducing energy consumption and emissions. Through capacity increase transformation, enterprises can not only improve production efficiency, but also achieve energy conservation and emission reduction, enhancing economic benefits and environmental protection levels. This transformation fully considers the compatibility of existing equipment and the needs of future development, ensuring the safe, stable, and efficient operation of the transformed system, and is an important means to promote the transformation of traditional industries towards modernization and greening.

[0003] However, the main disadvantages of the existing technology are the insufficient flexibility of the steam supply system, which is difficult to dynamically adapt to the industrial steam demand of multiple pressure levels, and it cannot take into account the efficient coordination of heating and industrial steam supply. The traditional scheme relies on a single extraction steam mode, with a weak redundancy mechanism and a relatively high risk of steam supply interruption; the high and low bypass systems are not fully integrated, resulting in relatively large energy losses and high operation and maintenance costs. At the same time, there is a lack of seasonal energy supply priority control strategies, the efficiency of combined heat and power generation is limited, and it is difficult to balance the contradiction between industrial extraction steam and heating demand, restricting the level of cascade utilization of energy. Summary of the Invention

[0004] The purpose of the present invention is to provide an industrial extraction steam capacity increase and transformation method based on optimizing steam turbines in order to solve the above-mentioned problems.

[0005] The technical solution adopted by the present invention is as follows: An industrial extraction steam capacity increase and transformation method based on optimizing steam turbines, the method comprising the following steps: S1: Based on the Chifeng energy development plan, clarify the industrial extraction steam demands of 1.2 MPa and 0.6 MPa in the industrial park, and combine the basis of the high back-pressure heating transformation of the existing Unit 1 and the zero output transformation of the low-pressure cylinder of Unit 2 to determine the capacity increase transformation target as an additional industrial extraction steam capacity of 240 t / h.

[0006] S2: Integrate the high and low pressure bypass systems of Unit 1 and Unit 2, and through the combined operation mode of the high bypass and the low bypass, provide extraction steam of 1.3 MPa and 0.7 MPa to the industrial steam supply header respectively, while retaining the heating extraction steam function to adapt to the flexibility requirements of the electricity spot market.

[0007] S3: Two electrically adjustable attemperators and pressure reducers are added to each unit to reduce the 3.93MPa steam after the high bypass to 1.3MPa, and adjust the temperature to 320℃ through attemperator water to meet the 1.2MPa industrial extraction steam demand; a 0.6MPa pressure reducer is added to reduce the 1.3MPa extraction steam to 0.7MPa for a second time.

[0008] S4: 12Cr1MoVG material main pipe and branch pipe are used to connect the high and low bypass systems. The main pipe is designed to be 273×14mm before temperature reduction and pressure reduction, and the branch pipe is designed to be 219×11mm. After temperature reduction and pressure reduction, the pipeline is made of No. 20 steel. The main steam supply pipeline is 426×9mm, and the 0.6MPa branch pipe is 530×11mm. Ensure that the flow velocity calibration value is within the range of 35~60m / s.

[0009] S5: Based on the newly added maximum industrial steam extraction flow of 320t / h, after reducing the original water treatment capacity, the water treatment system capacity is supplemented to 260t / h, and civil engineering and electrical interfaces are reserved to ensure water quality and steam supply stability.

[0010] S6: Units 1 and 2 serve as backup for each other. When a single unit supplies 1.2MPa extraction steam at full load, the other unit can independently undertake 0.6MPa extraction steam of 160t / h to ensure the continuity of steam supply.

[0011] S7: Based on the medium parameters and recommended flow rate range, check the inner diameter and material selection of the reheat hot section, cold section and temperature and pressure reduction pipes to ensure that the flow rate of the high-temperature reheat steam pipe is ≤65m / s and that of the low-temperature reheat steam pipe is ≤45m / s, and verify the pipe wall thickness and pressure resistance performance.

[0012] S8: Optimize the switching logic between high back pressure and low pressure cylinder zero output working conditions, give priority to ensuring 188t / h of heating steam extraction and 475GJ / h of high back pressure exhaust steam in winter, maximize industrial steam extraction output in the non-heating season, and balance the efficiency of cogeneration.

[0013] S9: After completing the equipment installation, simulate the combined high and low bypass steam supply, single bypass steam supply and extreme operating conditions test, calibrate the extraction steam pressure, temperature and flow parameters to ensure that the actual steam supply capacity reaches the design value of 240t / h, and verify the stability of the chemical water system and electrical control.

[0014] In a preferred embodiment, in step S1, according to the Chifeng Energy Development Plan, the industrial park needs to newly add industrial extraction steam with a pressure grade of 1.2 MPa and a flow rate of 100 tons per hour, as well as industrial extraction steam with a pressure grade of 0.6 MPa. Considering the existing equipment conditions, the high back-pressure heating transformation of Unit 1 has been completed, and the zero output of the low-pressure cylinder heating transformation of Unit 2 has been achieved. The transformation goal is to optimize the steam turbine system to increase the total industrial extraction steam supply capacity of the two units to 240 tons per hour and ensure the coordinated operation of heating and industrial steam supply. The current main steam flow rate is 480 tons per hour, the main steam pressure is 13.239 MPa, the temperature is 535 °C, and the enthalpy value is 3427 kJ / kg, providing basic parameter support for the transformation.

[0015] In a preferred embodiment, in step S2, the high-pressure bypass and low-pressure bypass systems of Unit 1 and Unit 2 are integrated, and the combined high-low bypass steam supply mode is adopted. The high bypass system reduces the main steam from 13.239 MPa to 3.93 MPa, the temperature drops from 535 °C to 384 °C, and the flow rate is 80 tons per hour; the low bypass system further reduces the hot reheat steam from 3.94 MPa to 1.3 MPa, and the temperature is adjusted from 535 °C to 320 °C, with a flow rate of 160 tons per hour. Through the diversion of the cold reheat steam and the hot reheat steam, a stable supply of 100 tons per hour of 1.2 MPa extraction steam and 60 tons per hour of 0.6 MPa extraction steam is achieved, while retaining 188 tons per hour of extraction steam from the cylinder exhaust for winter heating.

[0016] In a preferred embodiment, in step S3, each unit is equipped with two electric regulating desuperheating and pressure reducing valves. The parameters before the valve are 3.93 MPa and 535 °C, and the output after the valve is 1.3 MPa and 320 °C. The designed capacity is 140 tons per hour of input and 160 tons per hour of output. The desuperheating water is taken from the outlet of the condensate pump, with a pressure of 17 MPa, a temperature of 166.7 °C, and a flow rate of 7.7 tons per hour. A 0.6 MPa pressure reducing valve is added to further reduce the pressure of the 1.3 MPa extraction steam to 0.7 MPa. The flow rate before the valve is 85 tons per hour, and the temperature remains 320 °C, without additional desuperheating water, meeting the needs of low-pressure users.

[0017] In a preferred embodiment, in step S4, the main pipe before desuperheating and pressure reducing is made of 12Cr1MoVG material, with a specification of an outer diameter of 273 mm and a wall thickness of 14 mm, and the outer diameter of the branch pipe is 219 mm and the wall thickness is 11 mm. The main steam supply pipe after desuperheating and pressure reducing is made of 20# steel, with an outer diameter of 426 mm and a wall thickness of 9 mm, and the flow velocity is checked to be 51.0 m / s; the outer diameter of the 0.6 MPa branch pipe is 530 mm and the wall thickness is 11 mm, and the flow velocity is 46.32 m / s. The pipeline design strictly follows the flow velocity standards of 45 - 65 m / s for high-temperature reheat steam and 30 - 45 m / s for low-temperature reheat steam to ensure the safe and efficient operation of the system.

[0018] In a preferred embodiment, in step S5, in response to the demand for a maximum new industrial extraction steam flow rate of 320 tons per hour, after reducing the original chemical water treatment capacity, the system is expanded to 260 tons per hour. The new equipment includes a condensate water treatment unit and supporting pipelines. The desuperheating and pressure reducing valve desuperheating water flow rate is designed at 15 tons per hour. The pipeline material is 20# steel, with an outer diameter of 57 mm and a wall thickness of 3 mm, and a flow velocity of 2.13 m / s. A civil engineering interface for the chemical water system is reserved to ensure that the water quality meets the conductivity and hardness standards for steam supply.

[0019] In a preferred embodiment, in step S6, Unit 1 and Unit 2 are in standby for each other. When a single unit is operating at full load, the 1.2 MPa extraction steam supplies 100 tons per hour, and the 0.6 MPa extraction steam supplies 60 tons per hour; the other unit can independently undertake 160 tons per hour of 0.6 MPa extraction steam. The system is configured with redundant desuperheating and pressure reducing valves. The main pipe and branch pipes adopt a dual-channel design, and flow and pressure monitoring instruments are set at key nodes to ensure rapid switching in case of failure, and the risk of steam supply interruption approaches zero.

[0020] In a preferred embodiment, in step S7, the reheater hot section pipeline is made of 10CrMo910 material, with an outer diameter of 419 mm and a wall thickness of 22.2 mm, and a flow velocity of 50.06 m / s; the cold reheat pipeline is made of st45.8 / III material, with an outer diameter of 406.4 mm and a wall thickness of 14.2 mm, and a flow velocity of 38.62 m / s. The high-temperature reheater steam pipeline is pressure-resistant up to 3.94 MPa, and the low-temperature reheater pipeline is pressure-resistant up to 3.93 MPa. The wall thickness is verified by finite element analysis to ensure no creep risk during long-term operation at a high temperature of 535°C.

[0021] In a preferred embodiment, in step S8, heating steam supply is prioritized in winter. The high back-pressure exhaust steam volume of Unit 1 is 200 tons per hour, and the heat supply is 475 GJ per hour; the steam supply of Unit 2 under the condition of zero output of the low-pressure cylinder is 188 tons per hour, and the heat supply is 500 GJ per hour. In the non-heating season, it switches to the industrial extraction steam priority mode. By adjusting the opening degrees of the high and low bypasses, the main steam flow rate is dynamically distributed to achieve the goals of reducing the heating coal consumption by 6% and increasing the industrial extraction steam efficiency by 15%.

[0022] In a preferred embodiment, in step S9, during the trial operation stage, the combined supply of the high and low bypasses, single bypass supply, and extreme conditions are simulated. It is actually measured that the pressure fluctuation of the 1.2 MPa extraction steam is ≤0.05 MPa, the temperature error is ±3°C, and the flow deviation is ≤2%. The hardness of the water outlet of the chemical water system is ≤2 μmol / L, and the conductivity is ≤0.2 μS / cm, meeting the GB / T12145 standard. Finally, it is verified that the total steam supply of the two units reaches 240 tons per hour, the pipeline vibration value is <50 μm, and the equipment start-stop response time is <30 seconds, fully achieving the design indicators.

[0023] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: 1. In the present invention, by integrating the high and low bypass systems and optimizing the extraction steam structure, the steam supply flexibility and energy utilization efficiency are significantly improved. Through the combined high and low bypass steam supply mode, the system can dynamically allocate the supply ratio of 1.2 MPa and 0.6 MPa industrial extraction steam, which not only meets the steam demand of multiple pressure grades in the industrial park but also takes into account the priority of winter heating and heat supply. After the transformation, a single unit can independently undertake the extraction steam tasks of different pressure grades, and the two units are mutually backup, greatly enhancing the reliability and continuity of the steam supply system. At the same time, the optimized configuration of pipeline design and desuperheating and pressure reducing equipment not only reduces the energy loss during steam transmission but also extends the service life of the equipment and reduces the operation and maintenance costs through strict verification of materials and flow rates.

[0024] 2. In the present invention, the efficient balance of cogeneration is achieved through the coordinated control strategy. In the non-heating season, the system can maximize the output of industrial extraction steam, improving the unit load rate and economic benefits; in winter, the heat supply for heating is prioritized, and the power supply coal consumption is significantly reduced through the switching of high back pressure and zero output of the low-pressure cylinder technologies. The adaptation and expansion of the demineralized water system and the design of the redundancy mechanism further ensure the steam supply quality and system stability. The overall transformation not only improves the enterprise's production capacity but also strengthens the energy cascade utilization ability, providing technical support for the sustainable development of regional heat and power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is a system diagram of the industrial extraction steam transformation scheme in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiment

[0027] Refer to Figure 1-2 , An industrial extraction steam capacity increase transformation method based on an optimized steam turbine, comprising the following steps: S1: Based on the energy development plan of Chifeng, clarify the demand for new 1.2 MPa and 0.6 MPa industrial extraction steam in the industrial park, and determine the capacity increase transformation target as an additional 240 t / h industrial extraction steam capacity in combination with the existing high back pressure heating transformation of Unit 1 and the zero output transformation of the low-pressure cylinder of Unit 2.

[0028] S2: Integrate the high and low pressure bypass systems of units 1 and 2, and provide 1.3MPa and 0.7MPa extraction steam to the industrial steam supply manifold respectively through the joint operation mode of high bypass and low bypass, while retaining the heating extraction steam function to meet the flexibility needs of the electricity spot market.

[0029] S3: Two electrically adjustable attemperators and pressure reducers are added to each unit to reduce the 3.93MPa steam after the high bypass to 1.3MPa, and adjust the temperature to 320℃ through attemperator water to meet the 1.2MPa industrial extraction steam demand; a 0.6MPa pressure reducer is added to reduce the 1.3MPa extraction steam to 0.7MPa for a second time.

[0030] S4: 12Cr1MoVG material main pipe and branch pipe are used to connect the high and low bypass systems. The main pipe is designed to be 273×14mm before temperature reduction and pressure reduction, and the branch pipe is designed to be 219×11mm. After temperature reduction and pressure reduction, the pipeline is made of No. 20 steel. The main steam supply pipeline is 426×9mm, and the 0.6MPa branch pipe is 530×11mm. Ensure that the flow velocity calibration value is within the range of 35~60m / s.

[0031] S5: Based on the newly added maximum industrial steam extraction flow of 320t / h, after reducing the original water treatment capacity, the water treatment system capacity is supplemented to 260t / h, and civil engineering and electrical interfaces are reserved to ensure water quality and steam supply stability.

[0032] S6: Units 1 and 2 serve as backup for each other. When a single unit supplies 1.2MPa extraction steam at full load, the other unit can independently undertake 0.6MPa extraction steam of 160t / h to ensure the continuity of steam supply.

[0033] S7: Based on the medium parameters and recommended flow rate range, check the inner diameter and material selection of the reheat hot section, cold section and temperature and pressure reduction pipes to ensure that the flow rate of the high-temperature reheat steam pipe is ≤65m / s and that of the low-temperature reheat steam pipe is ≤45m / s, and verify the pipe wall thickness and pressure resistance performance.

[0034] S8: Optimize the switching logic between high back pressure and low pressure cylinder zero output working conditions, give priority to ensuring 188t / h of heating steam extraction and 475GJ / h of high back pressure exhaust steam in winter, maximize industrial steam extraction output in the non-heating season, and balance the efficiency of cogeneration.

[0035] S9: After completing the equipment installation, simulate the combined high and low bypass steam supply, single bypass steam supply and extreme operating conditions test, calibrate the extraction steam pressure, temperature and flow parameters to ensure that the actual steam supply capacity reaches the design value of 240t / h, and verify the stability of the chemical water system and electrical control.

[0036] In step S1, according to the Chifeng Energy Development Plan, the industrial park needs to newly add industrial extraction steam with a pressure grade of 1.2 MPa and a flow rate of 100 tons per hour, as well as industrial extraction steam with a pressure grade of .6 MPa. Considering the existing equipment conditions, the high back-pressure heating transformation has been completed for Unit 1, and the zero output of the low-pressure cylinder for heating transformation has been achieved for Unit 2. The transformation goal is to optimize the steam turbine system, increase the total industrial extraction steam supply capacity of the two units to 240 tons per hour, and ensure the coordinated operation of heating and industrial steam supply. The current main steam flow rate is 480 tons per hour, the main steam pressure is 13.239 MPa, the temperature is 535 °C, and the enthalpy value is 3427 kJ / kg, providing basic parameter support for the transformation.

[0037] In step S1, the supporting auxiliary facilities include: Atomizing make-up water deaeration device: After the industrial extraction steam capacity expansion transformation, with the increase in the industrial extraction steam volume, the steam volume discharged into the condenser is greatly reduced, and it is necessary to enter the condenser hot well in the form of make-up water. After a large amount of make-up water enters the condenser, it may cause a significant increase in the oxygen content of the condensate, and may cause the dissolved gas volume in the condensate to exceed the standard, which will cause corrosion hazards to equipment such as boilers and steam turbines. In particular, oxygen has the strongest corrosiveness to equipment, seriously affecting the reliability of the condensate-feed water system.

[0038] To ensure that the oxygen content of the condensate meets the design requirements and improve the service life of the equipment, it is necessary to remove the dissolved oxygen in the condensate as much as possible. It is necessary to carry out supporting transformation on the make-up water system of the existing condenser and newly add a make-up water atomizing deaeration device for the unit.

[0039] The temperature of the condenser make-up water is relatively low. It is sprayed into the condenser throat in the form of droplets through the newly added make-up water atomizing nozzle, and the steam exhausted from the steam turbine is used to fully heat the droplets. When the droplets are heated to equal or very close to the saturation temperature corresponding to their pressure, the oxygen in them will be completely separated from the make-up water droplets. The oxygen is discharged from the condenser through the vacuum extraction system, and the deaerated make-up water droplets flow to the bottom of the condenser or the hot well of the exhaust device, thus achieving the purpose of deaeration.

[0040] For this industrial extraction steam capacity expansion transformation, it is planned to add a set of atomizing make-up water deaeration devices to the condensers of Unit 1 and Unit 2 respectively to meet the make-up water deaeration requirements.

[0041] Desuperheating water system: According to the requirements of the industrial extraction steam capacity expansion transformation, this project needs to configure desuperheating and pressure-reducing equipment. The water source is taken from an appropriate position before the regulating valve at the outlet of the condensate pump, and the designed pressure is 1.5 MPa. At the same time, a small-flow bypass is considered for the desuperheating water system.

[0042] For this industrial extraction steam capacity increase transformation, 2 sets of regulating type desuperheating and pressure reducing valves are adopted, and the desuperheating water flow is controlled by electric regulation to ensure the stability of the steam parameters after pressure reduction. The desuperheating water pipeline is made of steel pipe with the material of 20 and the pipe diameter of φ57×3, and the length of each unit configuration is about 150 meters, meeting the requirements of industrial extraction steam capacity increase transformation. The system design fully considers the operation flexibility. The small flow bypass can ensure the stable supply of desuperheating water under low load conditions, and work together with the main road to ensure the safety and reliability of the desuperheating and pressure reducing process.

[0043] Cylinder-cutting heating and heat supply pipeline system: After the cylinder-cutting transformation of Unit 2 is completed, a DN800 heating and heat supply pipeline interface is reserved at the connecting pipe of the medium and low pressure cylinders. During the implementation of this project, it is planned to connect this pipeline to the DN1500 main heating pipeline.

[0044] The overall independent layout scheme is adopted. The DN800 heating and heat supply pipeline is laid along the operating floor of the main plant building, and a valve group composed of a safety valve, a pneumatic check valve, a hydraulic quick closing valve and an electric cut-off butterfly valve is configured in sequence. The valve group is synchronously arranged on the operating floor of Unit 2.

[0045] The pipeline is led from the area of Unit 2 to the area of Unit 1, and is independent of the original DN1000 heating pipeline of Unit 2 without merging. The original DN1000 heating pipeline of Unit 2 and the DN1000 heating pipeline of Unit 1 are merged into the DN1500 main heating pipeline in the area of Unit 1. The newly added DN800 pipeline extends along the A column of the turbine building from the inside of the plant, passes through the area of Unit 1 and then exits the turbine building, and adopts a high-position layout method along the roof of the external structures of the turbine building. Finally, it joins at a selected position on the path of the DN1500 main heating pipeline on the opposite side of the road outside the turbine building. The specific coordinates of this joining node need to be determined through structural load calculation to ensure safe connection with the existing DN1500 main heating pipeline.

[0046] It is recommended to install the DN800 pipeline and valve system for cylinder-cutting heating and heat supply of Unit 2 in this industrial extraction steam capacity increase transformation. By using an independent DN800 heating branch line, while meeting the new heating demand, it can avoid flow interference to the original heating pipe network. The valve group configuration realizes the functions of steam parameter regulation and safety protection. The high-position cross-regional layout optimizes the utilization efficiency of the plant area and reserves space for the subsequent expansion of heating load.

[0047] Intermediate pressure combined valve transformation: The intermediate connection valve parameter adjustment is a technical transformation scheme that adjusts the intermediate connection valve of the steam turbine to increase the high-pressure exhaust pressure, so as to reduce the pressure difference before and after the last two-stage diaphragms and moving blades of the high-pressure stage, ensure the safe operation of the steam turbine and meet the requirements of industrial extraction steam pressure parameters.

[0048] It is necessary to optimize and transform the internal structure of the medium-pressure combined valve, and cooperate with system tests and checks to ensure that the loads of key components of the steam turbine are controllable during industrial extraction steam, and at the same time achieve precise regulation of extraction steam parameters, providing a safe and reliable operation guarantee for industrial steam supply and heating.

[0049] Currently, the short-term new demand of Chifeng Energy is 85 t / h of industrial extraction steam with a parameter of 0.7 MPa. The current combined intermediate valve can be appropriately adjusted to meet the demand. It is recommended that the transformation work of the combined intermediate valve can be considered to be implemented step by step according to the growth of the gas consumption of industrial heat users. The transformation cost of about 4 medium-pressure combined valves is estimated to be about 30 million yuan.

[0050] For this industrial extraction steam capacity increase transformation, the transformation work of the medium-pressure combined valve is not considered for the time being.

[0051] In step S1, the preliminary layout and site selection of key equipment specifically include the following content: The newly added industrial steam supply pipelines for this time are respectively taken out from the reheater hot section of A and B. According to the existing space position in the Chifeng Energy plant, the newly added industrial steam supply pipelines are respectively led out from the reheater hot section pipelines of A and B on the 17.5 m layer of the deaerator coal bunker in the main plant building and then merged into one main pipe. An electric isolation valve, a pneumatic check valve and a desuperheating and pressure reducing valve are set on the main pipe. The valves and desuperheating and pressure reducing valves of the industrial steam supply pipelines of the two units are placed on the open space beside the deaerator on the 17.5 m layer of the deaerator coal bunker in the main plant building, which is convenient for later maintenance and repair.

[0052] After passing through the desuperheating and pressure reducing valve, the newly added industrial steam supply pipelines of the two units extend along the C row column of the main plant building towards the fixed end and are respectively incorporated into the industrial steam supply header arranged on the boiler operating layer platform. The industrial steam supply header is newly added for this transformation, and the capacity of the industrial steam supply header is designed according to the maximum extraction steam capacity after the transformation of the two units. Since only the Zhongse Zinc Industry user is considered for the steam supply pipeline after the industrial steam supply header for this time, according to the steam parameters of Zhongse Zinc Industry of 0.6 MPa and 310 °C, a secondary pressure reducing valve needs to be added after the industrial steam supply header, and the industrial steam supply header reserves interfaces for later users.

[0053] After the industrial steam supply pipeline in the plant area is led out from the industrial steam supply header, according to the current layout of the pipe racks in the plant area, there is no vacant position. The newly added industrial steam supply pipeline needs to build a new pipe rack. Since the position of the later industrial steam user interface is not yet clear, according to the opinion of Chifeng Energy, the heat pump drive steam pipeline on the existing pipe rack is removed, and the newly added industrial steam supply pipeline is arranged along the pipe rack to the west side of the plant area by using the vacant position after removal and is connected to the later built industrial steam supply pipeline outside the plant. When the direction of other industrial steam user interfaces is determined later, new plant area pipe racks will be added according to the actual situation.

[0054] Check and select the flow velocity of the main pipelines According to the "Design Code for Power Plant Power Piping GB 50764-2012" and the "Technical Regulations for the Design of Steam-Water Piping in Thermal Power Plants DLT 5054-1996", for single-phase fluids, the inner diameter of the pipeline should be calculated according to the following formula based on the recommended medium flow rate:

[0055] In the formula, ——Inner diameter of the pipe, mm; G——medium mass flow rate, t / h; v——specific volume of medium m3 / kg; ——Medium flow rate m / s; Q——medium volume flow rate m3 / h.

[0056] Based on this, the pipe diameters of the relevant pipelines for this industrial steam extraction capacity expansion project were calculated, and the recommended flow rate range is shown in Table 5-2.

[0057] Table 5-2 Recommended flow rate range

[0058] Based on the recommended flow rate, the diameters of the main high-temperature steam pipelines of this project, including the unit's reheat hot section, reheat cold section, high bypass front and rear pipelines, newly added desuperheating and pressure reducing front pipeline branches, main pipes, newly added industrial steam user pipelines, desuperheating water pipelines and reserved industrial steam user pipelines, are calculated. The main calculation results are detailed in the table below.

[0059] Table of results of pipe diameter verification for industrial steam extraction capacity expansion and renovation

[0060] Analysis of impact on unit operation safety When increasing the capacity of industrial steam extraction units, attention should be paid to the operational safety, protection measures and operating modes of the units after the transformation.

[0061] 1) Impact on Unit Operational Safety: We recommend adopting an operating strategy that appropriately matches "high bypass steam flow" with "low bypass steam flow - high bypass desuperheating water flow." By adding control logic, the high-pressure cylinder exhaust pressure and pressure cooker exhaust temperature are consistently maintained within an appropriately matched range. By adjusting the openings of the bypass valve and the intermediate-pressure combined regulating valve, the high-bypass desuperheating water flow is simultaneously controlled. This balances the turbine axial thrust while also achieving heat balance between the boiler's superheater and reheater, ensuring thermal balance between the boiler's superheater and reheater, as well as turbine axial thrust. Therefore, the industrial extraction steam capacity expansion solution has minimal impact on unit operational safety.

[0062] 2) Linkage protection measures for the unit under fault conditions such as high bypass malfunction and jamming: Compared with the normal operation conditions of the unit, when the high and low bypasses are combined for heat supply, the boiler load is significantly higher than the turbine load. To avoid accidents endangering the safe operation of the unit such as a rapid increase in the unit's electric load or a large fluctuation in the main steam pressure caused by situations like the interruption of the high bypass desuperheating water or the incorrect closing of the high bypass under extreme conditions such as a high heat supply load, it is recommended to add a protection logic for tripping the unit based on the growth rate of the main steam pressure and electric power in the control logic. When it is monitored that the growth rate and duration of the main steam pressure exceed the protection limit, trigger the tripping of the unit and boiler in linkage, and open the PCV to avoid damage to the unit equipment under the aforementioned extreme conditions.

[0063] 3) Operating mode: After the industrial extraction steam capacity expansion transformation, it is recommended to give priority to putting the low bypass into use and then the high bypass during operation; before putting the bypass into use, the unit must establish a certain vacuum; the opening of the pressure regulating valve of the low bypass is larger than that of the high bypass.

[0064] In step S2, integrate the high-pressure bypass and low-pressure bypass systems of Unit 1 and Unit 2, and adopt the combined high and low bypass steam supply mode. The high bypass system reduces the main steam from 13.239 MPa to 3.93 MPa, the temperature drops from 535 °C to 384 °C, and the flow rate is 80 tons per hour; the low bypass system further reduces the hot reheat steam from 3.94 MPa to 1.3 MPa, and the temperature is adjusted from 535 °C to 320 °C, with a flow rate of 160 tons per hour. Through the diversion of the cold reheat steam and hot reheat steam, a stable supply of 100 tons per hour of extraction steam at 1.2 MPa and 60 tons per hour of extraction steam at 0.6 MPa is achieved, and at the same time, 188 tons per hour of extraction steam from the middle exhaust of the cylinder cutting is reserved for winter heating.

[0065] Operating condition table for the condition of operating with industrial extraction steam and high back pressure, the condition of operating with industrial extraction steam and cylinder cutting, and the summer condition with industrial extraction steam Item Unit For 160t / h industrial + high back pressure For 160t / h industrial + cylinder cutting For 160t / h industrial summer condition For 85t / h industrial + high back pressure For 85t / h industrial + cylinder cutting For 85t / h industrial summer condition Power generation MW 86.2 68.9 94.4 84.4 66.4 92.7 Main steam flow on the boiler side t / h 480 480 480 385 385 385 Main steam flow on the turbine side t / h 353.2 353.2 353.2 317.9 317.9 317.9 Main steam pressure on the turbine side MPa 13.24 13.24 13.24 13.24 13.24 13.24 Main steam temperature on the turbine side °C 535 535 535 535 535 535 Exhaust steam pressure of high pressure cylinder MPa 3.78 3.78 3.78 3.03 3.03 3.03 Exhaust steam temperature of high pressure cylinder °C 379 379 379 360 360 360 High bypass flow t / h 126.8 126.8 126.8 67.1 67.1 67.1 High bypass desuperheating water flow t / h 13.2 13.2 13.2 7.9 7.9 7.9 Low bypass flow t / h 140 140 140 75 75 75 Low bypass desuperheating water flow t / h 20 20 20 11.6 11.3 11.3 1.3Mpa extraction steam flow t / h 100 100 100 0 0 0 1.3Mpa extraction steam pressure MPa 1.3 1.3 1.3 / / / 1.3Mpa extraction steam temperature ℃ 320 320 320 / / / 0.7Mpa extraction steam flow t / h 60 60 60 86.6 86.3 86.3 0.7Mpa extraction steam pressure MPa 0.7 0.7 0.7 0.7 0.7 0.7 0.7Mpa extraction steam temperature ℃ 313 313 313 313 313 313 Total industrial extraction steam volume t / h 160 160 160 86.6 86.3 86.3 Exhaust steam pressure of intermediate pressure cylinder MPa 0.29 0.29 0.29 0.29 0.29 0.29 Intermediate extraction steam flow t / h 0 195 0 0 195 0 Exhaust steam flow of low pressure cylinder t / h 207 20 200 207 20 200 Exhaust steam pressure of low pressure cylinder kPa 17.5 4.9 4.9 17.5 4.9 4.9 Heating supply GJ / h 485 490 0 485 490 0 In step S3, each unit is equipped with two electric regulating desuperheaters and pressure reducers. The parameters before the valve are 3.93 MPa and 535 °C, and the output after the valve is 1.3 MPa and 320 °C. The designed capacity is 140 tons per hour of input and 160 tons per hour of output. The desuperheating water is taken from the outlet of the condensate pump, with a pressure of 17 MPa, a temperature of 166.7 °C, and a flow rate of 7.7 tons per hour. Add a pressure reducer for 0.6 MPa to further reduce the 1.3 MPa extraction steam to 0.7 MPa. The flow rate before the valve is 85 tons per hour, and the temperature remains 320 °C, without additional desuperheating water, to meet the needs of low-pressure users.

[0066] In step S4, before desuperheating and depressurizing, the main pipe is made of 12Cr1MoVG material, with a specification of 273 mm in outer diameter and 14 mm in wall thickness. The outer diameter of the branch pipe is 219 mm and the wall thickness is 11 mm. After desuperheating and depressurizing, the main steam supply pipeline is made of 20# steel, with an outer diameter of 426 mm and a wall thickness of 9 mm, and the flow velocity is checked to be 51.08 m / s; the outer diameter of the 0.6 MPa branch pipe is 530 mm and the wall thickness is 11 mm, and the flow velocity is 46.32 m / s. The pipeline design strictly follows the flow velocity standards of 45 - 65 m / s for high-temperature reheated steam and 30 - 45 m / s for low-temperature reheated steam to ensure the safe and efficient operation of the system.

[0067] In step S5, for the demand of the maximum flow rate of the newly added industrial extraction steam of 320 t / h, after reducing the original chemical water treatment capacity, the system is expanded to 260 t / h. The newly added equipment includes a condensate water treatment unit and supporting pipelines. The desuperheating water flow rate of the desuperheater and pressure reducer is designed at 15 t / h. The pipeline material is 20# steel, with an outer diameter of 57 mm and a wall thickness of 3 mm, and the flow velocity is 2.13 m / s. A civil engineering interface for the chemical water system is reserved to ensure that the water quality meets the conductivity and hardness standards of steam supply.

[0068] In step S6, Unit 1 and Unit 2 are in standby for each other. When a single unit operates at full load, the 1.2 MPa extraction steam supplies 100 t / h, and the 0.6 MPa extraction steam supplies 60 t / h; the other unit can independently undertake 160 t / h of 0.6 MPa extraction steam. The system is configured with redundant desuperheaters and pressure reducers. The main pipe and branch pipes adopt a dual-channel design, and flow rate and pressure monitoring instruments are set at key nodes to ensure quick switching in case of failure and the risk of steam supply interruption approaches zero.

[0069] In step S7, the reheated hot section pipeline is made of 10CrMo910 material, with an outer diameter of 419 mm and a wall thickness of 22.2 mm, and the flow velocity is 50.06 m / s; the cold reheat pipeline adopts st45.8 / III material, with an outer diameter of 406.4 mm and a wall thickness of 14.2 mm, and the flow velocity is 38.62 m / s. The high-temperature reheated steam pipeline is pressure-resistant up to 3.94 MPa, and the low-temperature reheated pipeline is pressure-resistant up to 3.93 MPa. The wall thickness is verified by finite element analysis to ensure no creep risk during long-term operation at a high temperature of 535°C.

[0070] In step S8, heating steam supply is prioritized in winter. The high back-pressure exhaust steam volume of Unit 1 is 200 t / h, and the heat supply is 475 GJ / h; the steam supply of Unit 2 under the condition of zero output of the low-pressure cylinder is 188 t / h, and the heat supply is 500 GJ / h. In the non-heating season, it switches to the industrial extraction steam priority mode. By adjusting the opening degrees of the high and low bypasses, the main steam flow rate is dynamically distributed to achieve the goals of reducing the heating coal consumption by 6% and increasing the industrial extraction steam efficiency by 15%.

[0071] In step S9, during the trial operation phase, the combined supply of high and low bypasses, single bypass supply, and extreme conditions are simulated. The measured fluctuation of the 1.2 MPa extraction steam pressure is ≤ 0.05 MPa, the temperature error is ±3 °C, and the flow deviation is ≤ 2%. The hardness of the treated water system effluent is ≤ 2 μmol / L, and the conductivity is ≤ 0.2 μS / cm, meeting the GB / T 12145 standard. Finally, it is verified that the total steam supply of the two units reaches 240 tons per hour, the pipeline vibration value is < 50 μm, and the equipment start-stop response time is < 30 seconds, fully achieving the design indicators.

[0072] It can be seen from the above that: In the present invention, by integrating the high and low bypass systems and optimizing the extraction steam structure, the steam supply flexibility and energy utilization efficiency are significantly improved. Through the combined supply mode of high and low bypasses, the system can dynamically allocate the supply ratio of 1.2 MPa and 0.6 MPa industrial extraction steam, which not only meets the steam demand of different pressure grades in the industrial park but also takes into account the priority of winter heating supply. After the transformation, a single unit can independently undertake the extraction steam tasks of different pressure grades, and the two units are mutually backup, greatly enhancing the reliability and continuity of the steam supply system. At the same time, the optimized configuration of pipeline design and desuperheating and pressure-reducing equipment not only reduces the energy loss during steam transportation but also extends the service life of the equipment and reduces the operation and maintenance costs through strict verification of materials and flow rates.

[0073] In the present invention, the efficient balance of cogeneration is achieved through a coordinated control strategy. During the non-heating season, the system can maximize the output of industrial extraction steam, improving the unit load rate and economic benefits; in winter, the heating supply quantity is prioritized, and by switching between high backpressure and zero output of the low-pressure cylinder technologies, the power supply coal consumption is significantly reduced. The adaptation and expansion of the treated water system and the design of the redundancy mechanism further ensure the steam supply quality and system stability. The overall transformation not only improves the enterprise's production capacity but also strengthens the energy cascade utilization ability, providing technical support for the sustainable development of regional heating and power supply.

[0074] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements includes not only those elements but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article, or device including the element.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention 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 of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An industrial extraction steam capacity increase transformation method based on an optimized steam turbine, characterized in that: The method includes the following steps: S1: Identify the new industrial extraction steam demands of 1.2 MPa and 0.6 MPa in the industrial park. Based on the existing high back-pressure heating retrofit of Unit 1 and the zero output of the low-pressure cylinder retrofit of Unit 2, determine the capacity expansion retrofit target as adding an industrial extraction steam capacity of 240 t / h; S2: Integrate the high and low pressure bypass systems of Unit 1 and Unit 2. Through the combined operation mode of the high bypass and the low bypass, supply extraction steam of 1.3 MPa and 0.7 MPa to the industrial steam supply header respectively, while retaining the heating extraction steam function to meet the flexibility requirements of the electricity spot market; S3: Install two electric regulating desuperheaters on each unit, respectively reducing the 3.93 MPa steam after the high bypass to 1.3 MPa and adjusting the temperature to 320 °C through desuperheating water to meet the 1.2 MPa industrial extraction steam demand; Install a 0.6 MPa pressure reducer to secondarily reduce the 1.3 MPa extraction steam to 0.7 MPa; S4: Connect the high and low bypass systems with a main pipe and branch pipes made of 12Cr1MoVG material. The main pipe before desuperheating and pressure reduction is designed as 273×14 mm, and the branch pipes are 219×11 mm; After desuperheating and pressure reduction, the pipeline is made of 20# steel. The main steam supply pipeline specification is 426×9 mm, and the 0.6 MPa branch pipe is 530×11 mm to ensure that the verified flow velocity value is within the range of 35 - 60 m / s; S5: According to the maximum flow rate of the newly added industrial extraction steam of 320 t / h, after reducing the original chemical water treatment capacity, supplement the water treatment system capacity to 260 t / h, and reserve the civil engineering and electrical interfaces to ensure the water quality and steam supply stability; S6: Enable Unit 1 and Unit 2 to be backup for each other. When a single unit supplies 1.2 MPa extraction steam at full load, the other unit can independently undertake 160 t / h of 0.6 MPa extraction steam to ensure the continuity of steam supply; S7: Based on the medium parameters and the recommended flow velocity range, check the inner diameter and material selection of the reheater hot section, cold section and desuperheating and pressure reduction pipelines to ensure that the flow velocity of the high-temperature reheater steam pipeline ≤ 65 m / s, the low-temperature reheater steam pipeline ≤ 45 m / s, and verify the wall thickness and pressure resistance performance; S8: Optimize the switching logic between the high back-pressure and zero output of the low-pressure cylinder operating conditions. Prioritize ensuring 188 t / h of heating extraction steam and 475 GJ / h of high back-pressure exhaust steam in winter, and maximize the industrial extraction steam output in the non-heating season to balance the cogeneration efficiency; S9: After the equipment installation, simulate the combined steam supply of the high and low bypasses, single bypass steam supply and extreme condition tests, calibrate the extraction steam pressure, temperature and flow parameters to ensure that the actual steam supply capacity reaches the designed value of 240 t / h, and verify the stability of the chemical water treatment system and electrical control; 2. The industrial extraction steam capacity increase retrofit method based on an optimized steam turbine according to claim 1, characterized in that: In the step S1, according to the Chifeng energy development plan, the industrial park needs to newly add industrial extraction steam with a pressure grade of 1.2 MPa and 100 tons per hour, as well as industrial extraction steam with a pressure grade of 0.6 MPa; Considering the existing equipment conditions, the high back-pressure heating retrofit of Unit 1 has been completed, and the zero output of the low-pressure cylinder heating retrofit of Unit 2 has been achieved; The transformation goal is to increase the total industrial extraction steam supply capacity of the two units to 240 tons per hour by optimizing the steam turbine system and ensure the coordinated operation of heating and industrial steam supply; the current main steam flow rate is 480 tons per hour, the main steam pressure is 13.239 MPa, the temperature is 535 °C, and the enthalpy value is 3,427 kJ / kg, providing basic parameter support for the transformation.

3. The industrial extraction steam capacity increase transformation method based on an optimized steam turbine according to claim 1, wherein: In the step S2, the high-pressure bypass and low-pressure bypass systems of Unit 1 and Unit 2 are integrated, and the combined high-low bypass steam supply mode is adopted; the high bypass system reduces the main steam from 13.239 MPa to 3.93 MPa, the temperature drops from 535 °C to 384 °C, and the flow rate is 80 tons per hour; the low bypass system further reduces the hot reheat steam from 3.94 MPa to 1.3 MPa, and the temperature is adjusted from 535 °C to 320 °C, with a flow rate of 160 tons per hour; through the diversion of the cold reheat steam and the hot reheat steam, a stable supply of 100 tons per hour of 1.2 MPa extraction steam and 60 tons per hour of 0.6 MPa extraction steam is achieved, while retaining 188 tons per hour of extraction steam from the middle exhaust of the cylinder cutting for winter heating.

4. A method for industrial extraction steam capacity increase transformation based on an optimized steam turbine as claimed in claim 1, characterized in that: In the step S3, each unit is equipped with two electric regulating desuperheating and pressure reducing valves. The parameters before the valve are 3.93 MPa and 535 °C, and the output after the valve is 1.3 MPa and 320 °C. The designed capacity is 140 tons per hour of input and 160 tons per hour of output; the desuperheating water is taken from the outlet of the condensate pump, with a pressure of 17 MPa, a temperature of 166.7 °C, and a flow rate of 7.7 tons per hour; a 0.6 MPa pressure reducing valve is added to further reduce the 1.3 MPa extraction steam to 0.7 MPa. The flow rate before the valve is 85 tons per hour, and the temperature remains 320 °C, without additional desuperheating water, meeting the needs of low-pressure users.

5. A method for industrial extraction steam capacity increase transformation based on an optimized steam turbine as described in claim 1, characterized in that: In the step S4, the main pipe before desuperheating and pressure reduction is made of 12Cr1MoVG material, with a specification of an outer diameter of 273 mm and a wall thickness of 14 mm, and the outer diameter of the branch pipe is 219 mm and the wall thickness is 11 mm; the main steam supply pipe after desuperheating and pressure reduction is made of 20# steel, with an outer diameter of 426 mm and a wall thickness of 9 mm, and the flow velocity is checked to be 51.08 m / s; the outer diameter of the 0.6 MPa branch pipe is 530 mm and the wall thickness is 11 mm, and the flow velocity is 46.32 m / s; the pipeline design strictly follows the flow velocity standards of 45 - 65 m / s for high-temperature reheat steam and 30 - 45 m / s for low-temperature reheat steam to ensure the safe and efficient operation of the system.

6. The industrial extraction steam capacity increase transformation method based on an optimized steam turbine according to claim 1, wherein: In the step S5, in response to the demand for the maximum flow rate of the newly added industrial extraction steam of 320 tons per hour, after reducing the original chemical water treatment capacity, the system is expanded to 260 tons per hour; the newly added equipment includes a condensate water treatment unit and supporting pipelines. The desuperheating water flow rate of the desuperheating and pressure reducing valve is designed at 15 tons per hour. The pipeline material is 20# steel, with an outer diameter of 57 mm and a wall thickness of 3 mm, and the flow velocity is 2.13 m / s; a civil engineering interface for the chemical water system is reserved to ensure that the water quality meets the conductivity and hardness standards of steam supply.

7. The industrial extraction steam capacity increase transformation method based on an optimized steam turbine as claimed in claim 1, wherein: In step S6, Unit 1 and Unit 2 are in standby for each other. When a single unit operates at full load, the extraction steam at 1.2 MPa supplies 100 tons per hour, and the extraction steam at 0.6 MPa supplies 60 tons per hour. The other unit can independently undertake 160 tons per hour of extraction steam at 0.6 MPa. The system is configured with redundant desuperheating and pressure reducing valves. The main pipe and branch pipes adopt a dual-path design, and flow and pressure monitoring instruments are set at key nodes to ensure rapid switching in case of failure, and the risk of steam supply interruption approaches zero.

8. The industrial extraction steam capacity increase transformation method based on an optimized steam turbine as described in claim 1, characterized in that: In step S7, the reheater hot section pipe is made of 10CrMo910 material, with an outer diameter of 419 mm and a wall thickness of 22.2 mm, and a flow velocity of 50.06 m / s. The cold reheat pipe is made of st45.8 / III material, with an outer diameter of 406.4 mm and a wall thickness of 14.2 mm, and a flow velocity of 38.62 m / s. The high-temperature reheater steam pipe has a pressure resistance of 3.94 MPa, and the low-temperature reheater pipe has a pressure resistance of 3.93 MPa. The wall thickness is verified by finite element analysis to ensure no creep risk during long-term operation at a high temperature of 535°C.

9. The industrial extraction steam capacity increase retrofit method based on an optimized steam turbine according to claim 1, wherein: In step S8, heating steam supply is prioritized in winter. The high backpressure exhaust steam volume of Unit 1 is 200 tons per hour, and the heat supply is 475 GJ per hour. The steam supply of Unit 2 under the condition of zero output of the low-pressure cylinder is 188 tons per hour, and the heat supply is 500 GJ per hour. In the non-heating season, it switches to the industrial extraction steam priority mode. By adjusting the opening of the high and low bypasses, the main steam flow is dynamically distributed to achieve the goals of reducing the heating coal consumption by 6% and increasing the industrial extraction steam efficiency by 15%.

10. A method for industrial extraction steam capacity increase transformation based on an optimized steam turbine as described in claim 1, characterized in that: In step S9, during the trial operation stage, the combined supply of high and low bypasses, single bypass supply, and extreme conditions are simulated. The measured extraction steam pressure fluctuation at 1.2 MPa is ≤0.05 MPa, the temperature error is ±3°C, and the flow deviation is ≤2%. The hardness of the water output from the chemical water treatment system is ≤2 μmol / L, and the conductivity is ≤0.2 μS / cm, meeting the GB / T12145 standard. Finally, it is verified that the total steam supply of the two units reaches 240 tons per hour, the pipeline vibration value is <50 μm, and the equipment start-stop response time is <30 seconds, fully achieving the design indicators.

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