Industrial steam supply system transformation method

Abstract

The invention provides an industrial steam supply system transformation method, which belongs to the technical field of steam supply system transformation, adopts a cold and hot re-extraction steam combined supply method, performs adjustable transformation on a medium-pressure combined steam valve of an original unit, and improves the high exhaust pressure and reduces the front and rear pressure difference of high-pressure last two-stage clapboards and moving blades by turning down a medium-pressure regulating steam valve of a steam turbine. Safe operation of a steam turbine is guaranteed, meanwhile, it is guaranteed that steam extraction parameters meet the heat supply requirement, steam extraction heat supply transformation is conducted on a main steam pipeline, and extracted main steam is merged into a standby connector of an original steam header after temperature and pressure reduction. Energy conservation and consumption reduction are achieved, by optimizing a thermodynamic system, adopting a cold and hot re-extraction steam combined supply scheme and transforming a medium-pressure combined steam valve, the energy utilization efficiency is improved, power supply coal consumption is reduced, energy waste and pollutant emission are reduced, and the national energy conservation and emission reduction policy is met.

Description

Technical Field

[0001] This invention relates to the field of steam supply system renovation technology, and in particular to a method for renovating an industrial steam supply system. It is especially suitable for retrofitting existing 320MW condensing turbine units to achieve efficient and stable industrial steam supply, meet the steam energy demands of industrial production, and improve the overall energy utilization efficiency of power plants. Background Technology

[0002] Against the backdrop of a global effort to address climate change and vigorously promote carbon neutrality, my country is steadfastly implementing an energy development strategy that prioritizes both conservation and development, with conservation taking precedence. This strategy is not only crucial for energy security but also key to achieving sustainable development. Industrial steam supply, as an important manifestation of centralized heating energy-saving technology, perfectly aligns with the technological scope of energy conservation and comprehensive resource utilization, and has become an important direction for the development of the energy industry.

[0003] From an industry development perspective, advanced technologies such as combined heat and power (CHP) and waste heat cascade utilization are being increasingly widely applied and promoted. Through these technologies, power generation companies can achieve efficient energy utilization, reduce energy waste, and lower pollutant emissions. For example, utilizing existing CHP units, condensing generator units, and low-grade waste heat around cities and industrial parks for heating system upgrades can fully leverage the advantages of centralized heating by power generation companies while effectively eliminating small coal-fired, gas-fired, and oil-fired boilers within the heating and steam supply area. This significantly improves energy efficiency, reduces environmental pollution, and aligns with national energy policy guidelines and industry development trends.

[0004] The Beihai Tieshangang District (Coastal) Industrial Zone has experienced rapid development in recent years, with a surge in new heat users. This has led to a gradual increase in the external heat supply demand from the Guangxi Investment Beihai Power Plant. According to heat user data provided by the Guangxi Investment Beihai Power Plant, by the end of 2022, the plant's current heat load had reached 50 t / h. Entering 2023, the near-term heat load is projected to be approximately 27 t / h, with Shiluotai's heat load at approximately 7 t / h (requiring steam parameters of pressure ≥1.2 MPa and temperature ≥200℃) and Kaiyang Bio's heat load at approximately 20 t / h (requiring parameters of pressure ≥0.8 MPa and temperature ≥180℃). With the further development of the industrial zone, the number of heat users and steam demand will continue to increase, placing higher demands on the stability and reliability of the heating supply.

[0005] The existing heating system at Guangxi Investment Group Beihai Power Plant has revealed its inability to meet the steam demand of heat users during deep peak shaving and start-up / shutdown peak shaving. This not only affects the normal production and operation of heat users but also limits the power plant's own business expansion and economic benefits. The instability of the heating system may lead to production interruptions for heat users, causing economic losses; at the same time, it also prevents the power plant from fully leveraging its advantages and seizing market share in the face of ever-increasing heating demand. Therefore, upgrading and optimizing the existing heating system is urgently needed to adapt to the ever-changing heating demands and improve the system's safety, stability, and economy.

[0006] With rapid economic development, the demand for steam from industrial enterprises continues to rise. However, traditional small coal-fired industrial boilers are gradually being shut down by the government due to their low efficiency and failure to meet environmental standards. To address the imbalance between industrial steam supply and demand, retrofitting generator units for heating has become a widely adopted and effective approach. Currently, the industrial steam supply retrofitting of 320MW units has received widespread attention and in-depth research both domestically and internationally.

[0007] Abroad, some developed countries have achieved remarkable results in retrofitting 320MW generating units for industrial steam supply through advanced technologies and strategies. For example, some countries have adopted efficient heat recovery systems and advanced control technologies to achieve cascaded energy utilization, improve energy efficiency, reduce energy consumption and emissions, and create new profit growth points for enterprises. Domestically, numerous research institutions and enterprises are also actively exploring industrial steam supply retrofitting technologies for 320MW generating units. Through industry-academia-research cooperation, they are continuously optimizing retrofitting plans and promoting technological innovation and application. These retrofitting projects have not only improved energy efficiency and reduced energy consumption and emissions but also created new profit growth points for enterprises and promoted the sustainable development of the energy industry. Summary of the Invention

[0008] The purpose of this invention is to provide a method for retrofitting an industrial steam supply system, which solves the technical problem that existing heating systems cannot meet the steam demand of heat users during deep peak shaving and start-up / shutdown peak shaving of the unit.

[0009] Through comprehensive research and optimization of the thermal, control, and electrical systems, efficient and stable industrial steam supply is achieved to meet the ever-growing industrial steam demand in Tieshan Port District, Beihai City. Specifically, under single-unit heating conditions, reasonable parameters are set to meet the start-up, shutdown, and peak-shaving requirements of individual units, ensuring a steam supply of 130 t / h at 40%–95% load. Main steam is kept on standby, and each unit can supply more than 130 t / h of steam to meet the needs of heat users under various operating conditions. Simultaneously, under full-load conditions, the maximum single-unit (cold reheat + hot reheat) capacity can reach 80 t / h. Furthermore, through project research and industrial application, the layout of the centralized heating network in Tieshan Port Industrial Zone is improved, enhancing the safety and economy of the heating network, reducing environmental pollution emissions, and contributing to Beihai City's energy conservation and emission reduction goals and the development of a low-carbon economy.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An industrial steam supply system modification method is proposed, which adopts a combined cold and hot steam extraction method and modifies the adjustability of the intermediate-pressure combined steam valve of the original unit. By closing the intermediate-pressure regulating steam valve of the steam turbine, the high-pressure exhaust pressure is increased, the pressure difference before and after the last two stages of high-pressure diaphragms and moving blades is reduced, ensuring the safe operation of the steam turbine. At the same time, the extraction steam parameters are guaranteed to meet the heating requirements. The main steam pipeline is modified for extraction steam heating. The main steam extraction is desuperheated and depressurized and then connected to the original steam header spare interface.

[0011] Furthermore, in the combined cooling and heating steam extraction method, under medium and high loads, the low-temperature reheat steam is directly used for heating after pressure reduction, while the high-temperature reheat steam is simultaneously de-temperatured after pressure reduction and directly used for heating.

[0012] Furthermore, for 320MW-class subcritical units, the safe extraction rate of low-temperature reheat steam is 43-48 t / h, and the extraction capacity of high-temperature reheat steam for heating fluctuates with the load and exceeds the set value, with a safe extraction rate of 48-52 t / h. However, under the premise of making the intermediate-pressure combined steam valve adjustable and ensuring the safe operation of the unit, the maximum extraction capacity of high-temperature reheat steam for heating can be increased to 220-270 t / h.

[0013] Furthermore, for the existing heating systems of several units, an extraction steam port will be added to the main steam pipeline of each unit. The extraction steam capacity is designed to be 110-150t / h. An electric gate valve, a pneumatic check valve, and a pressure reducing valve will be installed on the extraction steam pipeline in sequence. After passing through pressure, temperature, and flow measurement devices, the steam will be connected to the backup interface of the heating header.

[0014] Furthermore, in accordance with the provisions of the "Design Code for Power Pipelines of Power Plants GB50764-2012" and the "Technical Specification for Design of Steam and Water Pipelines of Thermal Power Plants DLT5054-1996", the main pipelines were calculated, the inner diameter of the pipelines was calculated based on the medium flow velocity for single-phase fluids, and the high-temperature steam pipelines were studied and modified according to the recommended flow velocity. The desuperheating water pipelines and the unit makeup water pipelines were tested with the hot re-extraction desuperheating and pressure reducing device to ensure the stable operation of the heating system.

[0015] Furthermore, the adjustability is modified to allow for central valve parameter adjustment, and a redundant DCS control system is adopted to collect process parameters within the system. The system is connected to the power plant's original control system via communication, and the system is monitored on the operator station in the original control room. The monitoring and control of the turbine central valve, desuperheating and pressure reducing system, and check valves, quick-closing valves, and electric isolation valves on the extraction steam pipeline are incorporated into the turbine DEH system.

[0016] Furthermore, the monitoring and control of heating and steam supply are integrated into the unit's DCS, using remote I / O stations connected to the unit's DCS. The DCS remote I / O stations use the same hardware as the original unit's DCS. Operators in the control room can complete all monitoring functions for normal unit operation and, with the cooperation of designated on-site personnel, handle system malfunctions and accidents. Through redundant configuration, it is ensured that the normal operation of the communication system will not be affected by the failure of any data communication bus, and the availability of the control system reaches 99.9%. The signal processing of input thermocouples, RTDs, and transmitters is completed by different I / O modules, and the failure of a single I / O module will not cause any equipment failure or tripping.

[0017] Furthermore, the power supply is for the motors of electric valves, pressure matching devices, desuperheaters, and desuperheating and pressure reducing devices; the instrument power supply is for the instruments of pressure transmitters, temperature transmitters, and differential pressure transmitters. The power supply capacity and layout are planned reasonably, and reasonable power supply circuits and protection measures are designed to ensure the stability, reliability, and safety of the power supply system.

[0018] Through comprehensive research and optimization of the thermal, control, and electrical systems, efficient and stable industrial steam supply is achieved to meet the ever-growing industrial steam demand in Tieshan Port District, Beihai City. Specifically, under single-unit heating conditions, reasonable parameters are set to meet the start-up, shutdown, and peak-shaving requirements of individual units, ensuring a steam supply of 130 t / h at 40%–95% load. Main steam is kept on standby, and each unit can supply more than 130 t / h of steam to meet the needs of heat users under various operating conditions. Simultaneously, under full-load conditions, the maximum single-unit (cold reheat + hot reheat) capacity can reach 80 t / h. Furthermore, through project research and industrial application, the layout of the centralized heating network in Tieshan Port Industrial Zone is improved, enhancing the safety and economy of the heating network, reducing environmental pollution emissions, and contributing to Beihai City's energy conservation and emission reduction goals and the development of a low-carbon economy.

[0019] The present invention, by adopting the above-described technical solution, has the following beneficial effects: (1) This invention achieves energy saving and consumption reduction. By optimizing the thermal system, adopting a combined cold and hot steam extraction scheme and modifying the medium-pressure combined steam valve, the energy utilization efficiency is improved, the coal consumption for power supply is reduced, and energy waste and pollutant emissions are reduced, which is in line with the national energy conservation and emission reduction policy.

[0020] (2) It meets the steam demand and ensures that the external steam supply is more than 130t / h under 40%-95% load. The main steam backup steam source can provide more than 130t / h per unit. Under full load conditions, the maximum single unit (cold reheat + hot reheat) can reach 80t / h. It can meet the ever-increasing steam demand of heat users under various operating conditions and ensure the stable operation of industrial production.

[0021] (3) Improve the layout of the heating network. The project research and industrial application have improved the layout of the centralized heating network in Tieshangang Industrial Zone, laying a solid foundation for Guangtou Beihai Power Plant to take the lead in occupying and dominating the heating market in Tieshangang Industrial Zone.

[0022] (4) Improve safety and economy: The adoption of a redundant DCS control system improves the reliability and stability of the control system, ensuring timely handling of abnormal system operation and accident conditions, and guaranteeing the safe operation of the heating system. At the same time, the rational design of the electrical system improves the stability and economy of the power supply system and reduces operating costs. Attached Figure Description

[0023] Figure 1 This is a diagram showing the maximum heat supply condition of the thermal simulation model of Guangtou Beihai Power Plant in this embodiment of the invention; Figure 2 This is a 100% THA-maximum heat supply diagram of the thermal simulation model of Guangtou Beihai Power Plant in this embodiment of the invention; Figure 3 This is a diagram of the 75% THA-130t / h steam supply of the thermal simulation model of Guangtou Beihai Power Plant in this embodiment of the invention; Figure 4 This is a diagram of the 50% THA-130t / h steam supply of the thermal simulation model of Guangtou Beihai Power Plant in this embodiment of the invention; Figure 5 This is a diagram of the 40% THA-steam supply of 130t / h in the thermal simulation model of Guangtou Beihai Power Plant in this embodiment of the invention; Figure 6 This is a diagram of the boiler output of 1025t / h and steam supply of 130t / h in the thermal simulation model of Guangtou Beihai Power Plant in this embodiment of the invention; Figure 7 This is a schematic diagram of the air extraction pressure control principle in an embodiment of the present invention; Figure 8 This is a schematic diagram of the steam extraction pressure over-limit shutdown control principle in an embodiment of the present invention; Figure 9 This is a schematic diagram of the steam extraction control principle in an embodiment of the present invention. Detailed Implementation

[0024] 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 accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the present invention, and these aspects of the invention can be implemented even without these specific details.

[0025] To meet the long-term, stable heating demand of 150-300 t / h for a single unit at the Guangxi Investment Beihai Power Plant, this invention adopts a combined cold and hot steam extraction scheme and modifies the adjustableness of the original unit's intermediate-pressure regulating valve (intermediate valve parameter adjustment). By closing the intermediate-pressure regulating valve of the turbine, the high-pressure exhaust pressure is increased, reducing the pressure difference before and after the last two stages of the high-pressure diaphragm and moving blades, ensuring the safe operation of the turbine, and simultaneously ensuring that the extraction steam parameters meet the heating requirements. Furthermore, considering the power plant's need to participate in deep peak shaving of the power grid, to ensure heating reliability, the main steam pipeline is modified for extraction heating. The extracted main steam is desuperheated and depressurized before being connected to the original steam header's spare interface.

[0026] In combined cooling and heating systems, under medium-to-high load conditions, low-temperature reheat steam can be directly used for heating after depressurization, offering good economic efficiency. However, the extraction capacity is less limited by the safety and reliability of the boiler reheater. High-temperature reheat steam, after depressurization, has a higher temperature and requires simultaneous cooling, making it slightly less economical than low-temperature reheat steam, but offering a larger extraction capacity. For a 320MW subcritical unit, the safe extraction capacity of low-temperature reheat steam is approximately 45 t / h, while the extraction capacity of high-temperature reheat steam fluctuates significantly with load, with a safe extraction capacity of approximately 50 t / h. According to consultation with the turbine manufacturer, under the premise of adjusting the intermediate-pressure combined steam valve and ensuring safe unit operation, the maximum extraction capacity of high-temperature reheat steam for heating can be increased to approximately 250 t / h.

[0027] The specific renovation measures are as follows: Heating system for Unit 1: An extraction steam port is added to the main steam pipeline of Unit 1. The extraction steam capacity is designed to be 130t / h. An electric gate valve, a pneumatic check valve, and a pressure reducing valve are installed in sequence on the extraction steam pipeline. After passing through pressure, temperature, and flow measurement devices, the steam is connected to the backup interface of the heating header.

[0028] Heating system for Unit 2: An extraction port is added to the main steam pipeline of Unit 2. The extraction capacity is designed to be 130t / h. An electric gate valve, a pneumatic check valve, and a desuperheater / pressure reducer are installed sequentially on the extraction pipeline. After passing through pressure, temperature, and flow measurement devices, it is connected to the backup interface of the heating header.

[0029] Meanwhile, in accordance with the provisions of the "Design Code for Power Pipelines of Power Plants GB50764-2012" and the "Technical Specification for Design of Steam and Water Pipelines of Thermal Power Plants DLT5054-1996", the main pipelines were calculated, the inner diameter of the pipelines was calculated based on the medium flow velocity for single-phase fluids, and high-temperature steam pipelines were studied and modified for recommended flow velocities. Tests were conducted on the configuration of desuperheating water pipelines and unit makeup water pipelines for the hot re-extraction desuperheating and pressure reducing device to ensure the stable operation of the heating system.

[0030] In control systems, such as Figure 7-9 As shown, a redundantly configured DCS control system is used to collect process parameters within the system. This system connects to the power plant's existing control system via communication, enabling monitoring of the system from the existing control room operator station. Specifically: The monitoring and control of check valves, quick-closing valves, and electric disconnect valves on the turbine's central valve, desuperheating and pressure reducing system, and extraction steam pipeline are incorporated into the turbine's DEH system.

[0031] The monitoring and control of heating and steam supply are integrated into the unit's DCS, using remote I / O stations connected to the DCS. These remote I / O stations employ the same hardware as the original unit DCS. Operators in the control room can perform all monitoring functions for normal unit operation and, with the assistance of a small number of on-site personnel, handle system anomalies and accidents. Redundancy ensures that a failure in any data communication bus will not affect the normal operation of the communication system, and the control system availability reaches 99.9%. Signal processing for input thermocouples, RTDs, and transmitters is handled by different I / O modules; a failure in a single I / O module will not cause any equipment malfunction or tripping.

[0032] In the electrical system, the power supply system for the newly added heating station is studied, and the system design comprehensively considers the different needs of lighting, power supply, and instrument power supply. Power supply mainly includes motors for electric valves, pressure matching devices, desuperheaters, and desuperheating and pressure reducing actuators. Instrument power supply mainly includes pressure transmitters, temperature transmitters, and differential pressure transmitters. The power supply capacity and layout are rationally planned, and reasonable power supply circuits and protection measures are designed to ensure the stability, reliability, and safety of the power supply system. Simultaneously, energy conservation and environmental protection factors are considered to reduce energy consumption and operating costs.

[0033] The main objective of this invention is to address the problem that the existing heating system of the Guangxi Investment Beihai Power Plant cannot meet the steam demand of heat users during deep peak shaving and start-up / shutdown peak shaving. Through comprehensive research and optimization of the thermal, control, and electrical systems, efficient and stable industrial steam supply is achieved to meet the ever-growing industrial steam demand in Tieshan Port District, Beihai City. Specifically, under single-unit heating conditions, by setting reasonable parameters to meet the start-up / shutdown and peak shaving requirements of a single unit, it ensures a steam supply of 130 t / h at 40%–95% load, with main steam as backup. Each unit can supply more than 130 t / h of steam to meet the needs of heat users under various operating conditions. Simultaneously, under full load conditions, the maximum single-unit (cold reheat + hot reheat) capacity can reach 80 t / h. Furthermore, through project research and industrial application, the layout of the centralized heating network in Tieshan Port Industrial Zone will be improved, enhancing the safety and economy of the heating network, reducing environmental pollution emissions, and contributing to Beihai City's energy conservation and emission reduction goals and the development of a low-carbon economy.

[0034] Thermal system upgrade: When adding an extraction steam inlet to the main steam pipeline of Unit 1, the design strictly adhered to a 130t / h extraction capacity, ensuring the strength and sealing of the extraction pipeline. Electric gate valves, pneumatic check valves, pressure reducing valves, and other equipment were installed sequentially, with the installation positions and connection methods of each device strictly following the design drawings. During installation, the equipment was debugged and calibrated to ensure normal operation. When adding an extraction steam inlet to the main steam pipeline of Unit 2, the design was also based on a 130t / h extraction capacity, and electric gate valves, pneumatic check valves, desuperheating and pressure reducing devices, and other equipment were installed. The pipe diameter of the main pipelines was calculated according to the "Design Code for Power Plant Power Pipelines GB 50764-2012" and the "Technical Specification for Design of Steam and Water Pipelines in Thermal Power Plants DLT 5054-1996," based on the medium flow velocity. Strict pressure tests and sealing tests are conducted on the high-temperature steam pipelines and the desuperheating and pressure reducing devices, as well as the unit's makeup water pipelines, to ensure the stable operation of the heating system.

[0035] Control System Installation and Commissioning: A redundant DCS control system is adopted to ensure system reliability. During installation, hardware devices are installed and connected strictly according to the system architecture diagram to ensure correct connection of the data communication bus and stable signal transmission. When collecting process parameters within the system, high-precision sensors and transmitters are selected to ensure the accuracy of the collected data. When connecting to the power plant's existing control system via communication methods, multiple communication tests are conducted to ensure the timeliness and integrity of data transmission. System monitoring is implemented on the existing control room operator station, and the monitoring interface is optimized for ease of operation by operators. The monitoring and control of check valves, quick-closing valves, and electrically operated isolation valves on the turbine intermediate valve, desuperheating and pressure reducing system, and extraction steam pipeline are integrated into the turbine DEH system to ensure precise control of each valve. The monitoring and control of heating and steam supply are integrated into the unit DCS, using a remote I / O station connected to the unit DCS. The DCS remote I / O station uses the same hardware as the original unit DCS to ensure system compatibility.

[0036] Electrical System Construction: When designing the power supply system for the new heating station, the different needs for lighting, power supply, and instrument power supply are fully considered. The power supply capacity is rationally planned, and appropriate power sources and lines are configured according to the power requirements of power-consuming equipment such as electric valves, pressure matching devices, desuperheaters, and desuperheating and pressure reducing actuators. Independent power supply circuits are designed for instrument power supply equipment such as pressure transmitters, temperature transmitters, and differential pressure transmitters to ensure normal instrument operation. Reasonable power supply circuits and protection measures are designed, and overload protection and short-circuit protection devices are installed to ensure the safety of the power supply system. During construction, wiring and equipment installation are strictly carried out according to the electrical system diagram to ensure construction quality. From the perspective of core technical contributions, the thermal system diagram and control system architecture diagram are the most optimal and best reflect the invention's innovation and working logic. These two diagrams correspond to the invention's "core technical solution" and "reliable operation guarantee," respectively, and are key to supporting the overall technical effect. The specific working principle is as follows: Figure 1-6 As shown.

[0037] from Figure 1-6 As shown, a dual-guarantee heating architecture is clearly presented, consisting of "cold and hot steam extraction as the main supply + main steam extraction as a backup." The core logic is "load-appropriate steam extraction and backup for peak shaving." Medium- and high-load main steam supply: Low-temperature reheat steam is directly connected to the heating header after pressure reduction treatment without additional desuperheating, which has the best thermal economy and undertakes a basic steam supply of about 45t / h; High-temperature reheat steam is connected to the header after "pressure reduction + desuperheating" dual treatment. Although the economy is slightly lower, the steam supply is larger (up to 250t / h after modification), which, together with low-temperature reheat steam, meets the long-term stable steam supply demand of 150-300t / h.

[0038] Interlocking protection of intermediate-pressure combined steam valves: Adjustable control is achieved by modifying the intermediate-pressure combined valve. During operation, the valve is closed to increase the high-pressure exhaust pressure, reduce the pressure difference between the last two stages of the high-pressure turbine, avoid the safety risks of the unit body caused by steam extraction, and at the same time ensure that the extraction steam parameters (pressure, temperature) meet the requirements of the heat user.

[0039] Peak shaving / start-stop standby steam supply: The main steam of Unit 1 is connected to the header after being processed by "electric gate valve (on / off control) → pneumatic check valve (anti-backflow) → pressure reducing valve (pressure regulation)"; the main steam of Unit 2 is connected after being connected by the same type of valve + desuperheater and pressure reducer (temperature and pressure adjustment). When the unit is deeply shaving (below 40% load) or starting and stopping, if the main steam supply system is insufficient, the main steam standby circuit will be automatically activated to ensure that the steam supply of more than 130t / h is uninterrupted.

[0040] Stable coordination between pipelines and equipment: The inner diameter of all extraction steam pipelines is calculated based on a flow rate of 130t / h or higher, and pressure, temperature, and flow measurement devices are equipped for real-time monitoring. Equipment such as desuperheaters and check valves are matched according to the medium parameters to ensure that the parameters of steam are stable throughout the entire process of "extraction → treatment → transmission → grid connection", meeting the requirements of heat users such as 1.2MPa / 200℃ and 0.8MPa / 180℃.

[0041] With "redundant configuration + seamless integration" as its core, the system achieves coordinated controllability between the heating system and the original unit, ensuring high reliability (99.9% availability). Hardware redundancy backup: Dual data communication buses and redundant remote I / O stations are adopted. In the event of failure of any bus or I / O module, the backup module will automatically switch over without affecting data transmission and equipment control, thus avoiding heating interruption caused by a single point of failure.

[0042] Control function partition integration: The monitoring and control of core equipment on the turbine side (interlocking valve, desuperheating and pressure reduction system, extraction steam check valve / quick-closing valve) are directly integrated into the original turbine DEH system to ensure precise linkage and regulation between the unit and the heating extraction steam, and to avoid parameter conflicts.

[0043] Monitoring of the heating side (steam supply pressure, temperature, flow rate, and header status) is integrated with the original unit's DCS system via a remote I / O station, allowing operators to perform the entire process from the control room without the need for additional control consoles.

[0044] Signal distribution processing: Signals collected by thermocouples, pressure transmitters, etc. are distributed to different I / O modules for processing. A failure of a single module only affects the local signal and will not cause equipment to trip or the system to crash, thus further improving operational stability.

[0045] Matters not covered in this invention are common knowledge.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for modifying an industrial steam supply system, characterized in that: A combined cold and hot steam extraction method is adopted, and the intermediate-pressure combined steam valve of the original unit is modified to be adjustable. By closing the intermediate-pressure regulating steam valve of the steam turbine, the high-pressure exhaust pressure is increased, the pressure difference before and after the last two stages of high-pressure diaphragms and moving blades is reduced, ensuring the safe operation of the steam turbine. At the same time, the extraction steam parameters are guaranteed to meet the heating requirements. The main steam pipeline is also modified for extraction steam heating. The main steam extraction is desuperheated and depressurized and then connected to the original steam header spare interface.

2. The method for modifying an industrial steam supply system according to claim 1, characterized in that: In the combined cooling and heating steam extraction method, under medium and high loads, the low-temperature reheat steam is directly used for heating after pressure reduction, while the high-temperature reheat steam is depressurized and then directly used for heating.

3. The method for modifying an industrial steam supply system according to claim 2, characterized in that: For 320MW subcritical units, the safe extraction rate of low-temperature reheat steam is 43-48 t / h, and the extraction capacity of high-temperature reheat steam for heating fluctuates with the load and exceeds the set value, with a safe extraction rate of 48-52 t / h. However, under the premise of making the intermediate-pressure combined steam valve adjustable and ensuring the safe operation of the unit, the maximum extraction capacity of high-temperature reheat steam for heating can be increased to 220-270 t / h.

4. The method for modifying an industrial steam supply system according to claim 1, characterized in that: For the existing heating systems of several units, an extraction port will be added to the main steam pipeline of each unit. The extraction capacity is designed to be 110-150t / h. An electric gate valve, a pneumatic check valve, and a pressure reducing valve will be installed on the extraction pipeline in sequence. After passing through pressure, temperature, and flow measurement devices, the pipeline will be connected to the spare interface of the heating header.

5. The method for modifying an industrial steam supply system according to claim 2, characterized in that: In accordance with the provisions of "Design Code for Power Pipelines of Power Plants GB50764-2012" and "Technical Specification for Design of Steam and Water Pipelines of Thermal Power Plants DLT5054-1996", the main pipelines were calculated, the inner diameter of the pipelines was calculated based on the medium flow velocity for single-phase fluids, and the high-temperature steam pipelines were studied and modified according to the recommended flow velocity. The desuperheating water pipelines and the unit makeup water pipelines were tested with the hot re-extraction desuperheating and pressure reducing device to ensure the stable operation of the heating system.

6. The method for modifying an industrial steam supply system according to claim 1, characterized in that: Adjustability was upgraded to allow for central valve parameter adjustment. A redundant DCS control system was adopted to collect process parameters within the system. The system was connected to the power plant's existing control system via communication. The system was monitored from the operator station in the existing control room. The monitoring and control of check valves, quick-closing valves, and electric disconnect valves on the turbine central valve, desuperheating and pressure reducing system, and extraction steam pipeline were incorporated into the turbine DEH system.

7. The method for modifying an industrial steam supply system according to claim 6, characterized in that: The monitoring and control of heating and steam supply are integrated into the unit's DCS. A remote I / O station is connected to the unit's DCS. The DCS remote I / O station uses the same hardware as the original unit's DCS. Operators in the control room can complete all monitoring functions for normal unit operation. With the cooperation of designated on-site personnel, they can handle abnormal system operation and accident conditions. Through redundant configuration, it is ensured that the normal operation of the communication system will not be affected when any data communication bus fails. The availability of the control system reaches 99.9%. The signal processing of input thermocouples, RTDs and transmitters is completed by different I / O modules. The failure of a single I / O module will not cause any equipment failure or tripping.

8. The method for modifying an industrial steam supply system according to claim 1, characterized in that: The power supply is for the motors of electric valves, pressure matching devices, desuperheaters, and desuperheating and pressure reducing devices. The instrument power supply is for the instruments of pressure transmitters, temperature transmitters, and differential pressure transmitters. The power supply capacity and layout should be planned reasonably, and reasonable power supply circuits and protection measures should be designed to ensure the stability, reliability, and safety of the power supply system.

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