Cold-state starting method of coal-fired unit without auxiliary steam source
By installing a micro-oil ignition device on the boiler's hot primary air duct and establishing a self-steaming closed loop, the dependence on cold start-up of coal-fired units was solved, enabling rapid start-up and improved safety under conditions without external steam.
Patent Information
- Application Number
- CN202510931384.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-07
- Publication Date
- 2025-10-31
AI Technical Summary
Traditional coal-fired power units rely on start-up boilers or temporary boiler steam during cold starts, which makes it difficult to guarantee equipment performance and prevents them from starting in the event of a plant-wide power outage, affecting both the power plant and the power grid.
A micro-oil ignition device is installed on the hot primary air duct on one side of the boiler. The boiler is ignited by igniting pulverized coal with fuel oil and compressed air. The boiler itself generates steam to establish a self-steaming closed loop, including main steam and reheat steam circulation, forming a dual self-steaming system to ensure normal steam use and vacuum extraction of the shaft seal system.
It enables the complete cold start of coal-fired power units without the need for a start-up boiler, boiler oil burner and matching fuel oil tank, or temporary auxiliary steam, thus shortening the start-up time and saving costs.
Smart Images
Figure CN120868422A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal-fired power unit technology, and in particular to a cold start method for a coal-fired power unit without an auxiliary steam source. Background Technology
[0002] Traditional coal-fired power units require a dedicated start-up boiler or temporary boiler steam for cold starts. The purpose of the start-up boiler is to supply steam to the auxiliary steam header during the startup of the first coal-fired unit. The auxiliary steam header then supplies steam to users such as turbine shaft seal steam, steam driven by steam-driven feedwater pumps, deaerator heating steam, boiler air preheater soot blowing steam, and plasma air heater heating steam, thus enabling the coal-fired power unit to start up.
[0003] As the unit's operation becomes increasingly stable, the start-up boiler remains in a state of shutdown for extended periods, making it difficult to guarantee its equipment performance. In the event of a plant-wide power outage and the inability to use the start-up boiler, the coal-fired unit will face the predicament of being unable to start up from a completely cold state, which will have a significant negative impact on both the power plant and the power grid. Summary of the Invention
[0004] The purpose of this invention is to provide a cold start control method and system for coal-fired power units, which can achieve a fully cold start of the coal-fired power unit without a start-up boiler, boiler oil burner and matching fuel oil tank, and temporary auxiliary steam.
[0005] This invention provides a cold start method for a coal-fired power unit without an auxiliary steam source, comprising:
[0006] Install a micro-oil ignition device on one side of the hot primary air duct of the boiler in the coal-fired unit;
[0007] The micro-oil ignition device is activated to ignite the pulverized coal in the hot primary air duct using fuel oil and compressed air, thus achieving boiler ignition.
[0008] After the boiler is successfully ignited, the main steam and reheat steam of the boiler are heated and pressurized; the reheat steam is depressurized by the high-pressure bypass valve and then connected to the cold reheat pipeline and introduced into the high-pressure auxiliary manifold.
[0009] When the pressure of the reheat steam reaches the preset first pressure threshold, steam is supplied to the shaft seal system to warm the pipes. Steam is supplied to the shaft seal system through the high auxiliary header to form the first self-steam closed loop.
[0010] When the pressure of the main steam reaches the preset second pressure threshold, the shaft seal system drain warming and the small turbine shaft seal system drain warming are performed. At the same time, the main steam pipeline is adjusted to directly connect the main steam to the turbine shaft seal system, forming a second self-steam closed loop.
[0011] Steam is supplied to the gas turbine unit shaft seal through the first self-steam supply closed loop and the second self-steam supply closed loop. When the shaft seal is in normal operation, a vacuuming operation is performed and the bypass system is activated.
[0012] After the bypass system is put into operation, the boiler is heated and pressurized, and the small turbine is started up and warmed up through the high-voltage auxiliary header to realize the turbine start-up;
[0013] When the primary air temperature at the air preheater outlet exceeds the preset air temperature threshold, the micro-oil ignition device is deactivated, completing the cold start of the coal-fired unit.
[0014] As an improvement to the above solution, the micro-oil ignition device includes an oil and gas supply module, a burner module, and a DCS control module.
[0015] The oil and gas supply module provides fuel and oxygen required for combustion to the burner module; the burner module includes an ignition gun and two atomizing micro-oil guns, with one atomizing micro-oil gun in operation and the other in standby mode; the DCS control module controls the opening and closing of the micro-oil ignition device.
[0016] As an improvement to the above solution, the step of activating the micro-oil ignition device to ignite pulverized coal in the hot primary air duct using fuel oil and compressed air to achieve boiler ignition includes:
[0017] After taking measures to prevent the fan on the side where the non-oil ignition device is installed in the hot primary air duct from reversing, the boiler is purged.
[0018] Fill the boiler with water. After the boiler is full of water, start the boiler water circulation pump and start the flue gas system to purge the furnace. After the furnace is purged, close the primary air connection damper and start the primary air fan on the side where the micro oil ignition device is installed. At the same time, keep the primary air fan outlet damper and its corresponding air preheater outlet damper on the side where the non-micro oil ignition device is installed closed.
[0019] When the pressure of the primary air main pipe increases to the preset third pressure threshold, the start-up mill outlet damper, the start-up mill primary air shut-off damper and the hot air damper are opened, and the mill bypass damper is opened to 50% to warm up the mill.
[0020] Maintain the fuel pressure within the preset first pressure range, and open the manual valves of the furnace air duct micro-oil ignition fuel system and compressed air system.
[0021] Open the purge valve to purge the hot primary air duct. After purging, put the micro oil ignition device into the ignition and control the primary air duct wall temperature at the preset first temperature threshold. At the same time, the air preheater performs soot blowing by the sonic soot blower.
[0022] When the outlet temperature of the coal mill separator reaches the preset second temperature threshold, the coal mill is started to introduce pulverized coal into the air duct, thereby igniting the boiler.
[0023] As an improvement to the above scheme, after successful boiler ignition, the main steam and reheat steam of the boiler are heated and pressurized; the reheat steam is depressurized by a high-pressure bypass valve and then connected to a cold reheat pipeline, and introduced into a high-pressure auxiliary manifold, including:
[0024] After the boiler is successfully ignited, open the boiler EBV valve, open the boiler 5% start-up drain, open the boiler superheater and reheater vent valves, and at the same time keep the turbine side drain closed to heat up and pressurize the main steam of the boiler.
[0025] Open the high-pressure bypass valve, and the main steam and the reheat steam after being depressurized by the high-pressure bypass valve are connected to the cold reheat pipeline to form reheat steam;
[0026] Close the high-pressure bypass spray desuperheating water shut-off valve, open the high-pressure drain check valve and drain water to the trench drain valve, check and open the electric and manual doors of the cold reheat supply high auxiliary manifold to introduce reheat steam into the high auxiliary manifold.
[0027] Open the manual drain valve to warm up the pipes and increase the temperature and pressure of the boiler's reheat steam.
[0028] As an improvement to the above scheme, when the pressure of the reheat steam reaches a preset first pressure threshold, steam is supplied to the shaft sealing system to warm the pipes. Steam is supplied to the shaft sealing system through the high-voltage auxiliary header to form a first self-steam supply closed loop, including:
[0029] When the main steam pressure reaches the preset fourth pressure threshold, close the boiler-side vent valve;
[0030] When the reheat steam pressure reaches the preset fifth pressure threshold, close the manual valve of the drain ditch after the high-pressure non-return valve, and close the drain valves of each drain ditch slightly.
[0031] When the steam drum pressure reaches the preset sixth pressure threshold, the boiler 5% bypass drain is shut off; when the steam drum pressure reaches the preset seventh pressure threshold, the EBV valve is shut off.
[0032] When the reheat steam pressure reaches the preset first pressure threshold, steam is supplied to the shaft seal system through the cold reheat shaft seal electric valve to warm the pipes. The drainage of each filter screen in the shaft seal system is checked locally to ensure that steam is supplied to the shaft seal system, thus forming the first self-steam closed loop.
[0033] As an improvement to the above scheme, when supplying steam to the shaft seal system, if the shaft seal steam supply temperature is lower than the preset third temperature threshold, the shaft seal steam supply main pipe electric heater is activated, and the heater is activated and deactivated according to the shaft seal steam supply temperature.
[0034] As an improvement to the above scheme, when the pressure of the main steam reaches a preset second pressure threshold, the condensate warming of the shaft seal system and the small turbine shaft seal system is performed, and the main steam pipeline is adjusted to directly connect the main steam to the turbine shaft seal system, forming a second self-steam closed loop, including:
[0035] When the pressure of the main steam reaches the preset second pressure threshold, the shaft seal system drain warming and the small turbine shaft seal system drain warming are performed.
[0036] Open the manual and electric valves of the main steam supply shaft seal steam source, slightly open the main steam supply shaft seal steam inlet adjustment valve, and open the drain from the main steam pipeline to the shaft seal. During the draining process, keep the condenser body's expansion spray continuously open so that the main steam can be directly connected to the turbine shaft seal system, forming a second self-supply closed loop.
[0037] As an improvement to the above solution, the step of supplying steam to the gas turbine unit shaft seal through the first self-steam supply closed loop and the second self-steam supply closed loop, and performing a vacuuming operation and activating the bypass system when the shaft seal is in normal operation, includes:
[0038] Steam is supplied to the shaft seals of the gas turbine unit through the first self-steam supply closed loop and the second self-steam supply closed loop to ensure normal pressure;
[0039] Once the shaft sealing system is in normal operation, perform a vacuuming operation.
[0040] When the unit vacuum reaches the preset first pressure threshold, open all drains from the unit to the condenser and open the drains before and after the low-pressure bypass electric valve.
[0041] When the unit vacuum reaches the preset second pressure threshold, the low-pressure bypass electric main valve is slowly opened, and the low-pressure bypass valves on sides A and B are opened by 5%, thus activating the bypass system; the second pressure threshold is greater than the first pressure threshold.
[0042] As an improvement to the above scheme, after the bypass system is put into operation, the boiler is heated and pressurized, and the small turbine is started up and warmed up through the high-voltage auxiliary header to realize the turbine start-up, including:
[0043] After the bypass system is put into operation, the boiler is heated and pressurized, and all vent and drain valves on the furnace side are checked and confirmed to be closed.
[0044] When the pressure of the high-pressure auxiliary manifold reaches the preset eighth pressure threshold, the blower heater and boiler are put into operation for continuous soot blowing in the air preheater.
[0045] Based on the steam source of the high-auxiliary header, the small turbine is started and warmed up;
[0046] Adjust the turbine startup parameters according to the startup conditions, and then start the turbine startup.
[0047] As an improvement to the above scheme, when the primary hot air temperature at the air preheater outlet exceeds a preset air temperature threshold, the micro-oil ignition device is deactivated to complete the cold start of the coal-fired unit, including:
[0048] When the primary hot air temperature at the air preheater outlet exceeds the preset air temperature threshold, the micro-oil ignition device is deactivated.
[0049] Start the primary air fan on the side where the non-oil ignition device is installed in the hot primary air duct to balance the output of the primary air fans on both sides and complete the cold start of the coal-fired unit.
[0050] Perform grid connection operations for coal-fired power units.
[0051] Compared with existing technologies, this invention discloses a cold start method for coal-fired power units without auxiliary steam sources. It utilizes a micro-oil ignition device installed in the boiler's hot primary air duct to meet the separator outlet temperature requirements for pulverizer ignition, solving the problem of air preheater steam blowing being impossible without steam. After unit ignition and startup, self-generated steam is used to restore normal steam supply to the auxiliary steam and shaft seal systems, forming a dual self-steam supply, enabling rapid unit startup and gradually initiating turbine shaft seal vacuuming operations. As the hot primary air temperature gradually rises, the micro-oil ignition device is discontinued. Once the unit reaches the start-up conditions, turbine startup and generator grid connection are performed. This invention is applicable to the fully cold start of coal-fired power units without a start-up boiler, boiler oil burner and associated fuel oil tank, and temporary auxiliary steam, effectively shortening startup time and saving startup costs. Attached Figure Description
[0052] Figure 1 This is a schematic flowchart of the steps of a cold start method for a coal-fired unit without an auxiliary steam source provided in an embodiment of the present invention;
[0053] Figure 2 This is a schematic diagram of the structure of a micro-oil ignition device provided in an embodiment of the present invention;
[0054] Figure 3 This is a schematic diagram of a boiler provided in an embodiment of the present invention. Detailed Implementation
[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0056] In the description and claims, it should be understood that the terms "first," "second," etc., used in the description and claims are only for the purpose of distinguishing the description of the same technical features, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, nor necessarily the order of description or chronological order. The terms are interchangeable where appropriate. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.
[0057] In existing boiler ignition methods, plasma burners are generally used for plasma ignition. Without a boiler steam supply for startup, and without auxiliary steam to heat the plasma air heater, the plasma burner cannot ignite the boiler. Furthermore, the lack of auxiliary steam also prevents operations such as air preheater steam soot blowing and turbine shaft seal vacuuming. Therefore, auxiliary steam is essential for the startup of current coal-fired units.
[0058] Based on the above considerations, this invention provides a cold start method for coal-fired power units without an auxiliary steam source. Please refer to [link to relevant documentation]. Figure 1 In this embodiment, the cold start method for the coal-fired unit without an auxiliary steam source is specifically executed through steps S1 to S8:
[0059] S1. Install a micro-oil ignition device on one side of the primary hot air duct of the boiler of the coal-fired unit.
[0060] The micro-oil ignition device is the core ignition equipment for the entire cold start. In this embodiment of the invention, by installing the micro-oil ignition device, the requirements of the separator outlet temperature for the ignition of the coal mill plasma air heater can be met, replacing the need for traditional plasma air heater steam heating or boiler fuel oil burner ignition, without relying on the boiler to generate auxiliary steam.
[0061] S2. Start the micro-oil ignition device to ignite the pulverized coal in the hot primary air duct using fuel oil and compressed air, thereby igniting the boiler.
[0062] S3. After the boiler is successfully ignited, the main steam and reheat steam of the boiler are heated and pressurized; the reheat steam is depressurized by the high-pressure bypass valve and then connected to the cold reheat pipeline and introduced into the high-pressure auxiliary manifold.
[0063] In this embodiment of the invention, the reheat steam generated by the boiler itself is used to establish a steam cycle, eliminating the need for external auxiliary steam and reducing dependence on external systems.
[0064] S4. When the pressure of the reheat steam reaches the preset first pressure threshold, steam is supplied to the shaft seal system to warm the pipes. Steam is supplied to the shaft seal system through the high auxiliary header to form the first self-steam closed loop.
[0065] Traditional startup requires steam from a neighboring machine or other steam source to supply the shaft seals, while the embodiments of the present invention can achieve self-steam supply, providing steam to the shaft seal system and other auxiliary equipment through a high-pressure auxiliary steam header, which can save energy and startup time.
[0066] S5. When the pressure of the main steam reaches the preset second pressure threshold, perform condensate warming of the shaft seal system and the small turbine shaft seal system, and at the same time adjust the main steam pipeline to directly connect the main steam to the turbine shaft seal system to form a second self-supply closed loop.
[0067] In addition to the first self-steaming closed loop, main steam will be introduced into the turbine shaft sealing system to replace part of the reheat steam supply, forming a dual-steam-source self-steaming closed loop. This further improves the stability of the shaft sealing steam supply, ensuring that the shaft sealing system has a reliable steam source at different pressure stages and enhancing the safety of the startup process.
[0068] S6. Steam is supplied to the gas turbine unit shaft seal through the first self-steam closed loop and the second self-steam closed loop. When the shaft seal is in normal operation, a vacuuming operation is performed and the bypass system is activated.
[0069] After establishing the turbine shaft seal seal by supplying steam through the shaft seal, the vacuum pump is started to extract the air from the turbine cylinder and condenser, creating a vacuum environment and creating conditions for the turbine to start up.
[0070] After the bypass system is put into operation (S7), the boiler is heated and pressurized, and the small turbine is started up and warmed up through the high-voltage auxiliary header to realize the turbine start-up.
[0071] S8. When the primary air temperature at the air preheater outlet is greater than the preset air temperature threshold, the micro-oil ignition device is deactivated to complete the cold start of the coal-fired unit.
[0072] As the temperature of the primary hot air gradually increases, the micro-oil ignition device is deactivated. Once the conditions for unit start-up are met, the turbine start-up and generator grid connection operations can be carried out to start the coal-fired unit.
[0073] The above scheme achieves boiler ignition by setting a micro-oil ignition device in the hot primary air duct, and constructs a dual self-steam closed-loop system based on the boiler's own combustion and steam circulation, effectively realizing the self-supply start-up of the unit system. It is applicable to the full cold start-up of coal-fired units without a start-up boiler, boiler oil burner and matching fuel oil tank, and temporary auxiliary steam, and can effectively shorten the start-up time and save start-up costs.
[0074] In a preferred embodiment, the micro-oil ignition device includes an oil / gas supply module, a burner module, and a DCS control module;
[0075] The oil and gas supply module provides fuel and oxygen required for combustion to the burner module; the burner module includes an ignition gun and two atomizing micro-oil guns, with one atomizing micro-oil gun in operation and the other in standby mode; the DCS control module controls the opening and closing of the micro-oil ignition device.
[0076] The micro-oil ignition device, through the configuration of an oil and gas supply module, a burner module, and a DCS control module, differs from traditional micro-oil ignition. In this embodiment of the invention, there is no need to build a new oil tank area; only a small mobile oil station needs to be built, thus eliminating fire hazards.
[0077] The atomizing micro-oil gun employs a simple atomization method. Its working principle involves fuel entering through the inlet holes on the pressurized fuel gun's distributor plate and converging into the corresponding annular groove. It then flows tangentially into the swirl chamber through the tangential grooves on the swirl vane, generating a strong swirling flow. Finally, it enters the atomizing vane and exits through the central hole, forming a hollow conical atomized airflow composed of droplets. As the oil flow exits the nozzle, a turbulent oil film is formed. The turbulent pulsation creates uneven ripples on the surface of the conical oil film. The large relative velocity and contact surface between the oil film and the surrounding gas allow the oil film to overcome surface tension and break into fine droplets, forming an oil mist. This type of fuel gun has a simple structure, is less prone to clogging, and exhibits strong operational stability. It can maintain the reliable operation of the duct combustion heating system, improve combustion efficiency, reduce black smoke generation during unit startup, replace traditional heavy oil, and meet the unit's ultra-low emission requirements.
[0078] Please see Figure 2 The oil and gas supply section provides fuel and oxygen for combustion to the micro-oil ignition device through pipelines and valves, and ensures fuel quality by installing filters on the oil pipeline. The burner section consists of an ignition gun, an atomizing micro-oil gun, a flame detector probe, and a flame temperature probe, which can achieve more than 99.5% complete combustion of fuel to heat the primary air to the specified temperature during the initial startup of the unit. The DCS control section incorporates information such as the temperature and air volume of the hot primary air duct at the coal mill inlet to determine whether the startup conditions of the device are met. It has functions of manual and automatic startup, low air volume protection, over-temperature protection, and fire extinguishing protection.
[0079] In a preferred embodiment, step S2, starting the micro-oil ignition device, ignites the pulverized coal in the hot primary air duct using fuel oil and compressed air to achieve boiler ignition, includes:
[0080] After taking measures to prevent the fan on the side where the non-micro-oil ignition device is installed in the hot primary air duct from reversing, the boiler is purged.
[0081] Fill the boiler with water. After the boiler is full of water, start the boiler water circulation pump and start the flue gas system to purge the furnace. After the furnace is purged, close the primary air connection damper and start the primary air fan on the side where the micro oil ignition device is installed. At the same time, keep the primary air fan outlet damper and its corresponding air preheater outlet damper on the side where the non-micro oil ignition device is installed closed.
[0082] When the pressure of the primary air main pipe increases to the preset third pressure threshold, the start-up mill outlet damper, the start-up mill primary air shut-off damper and the hot air damper are opened, and the mill bypass damper is opened to 50% to warm up the mill.
[0083] Maintain the fuel pressure within the preset first pressure range, and open the manual valves of the furnace air duct micro-oil ignition fuel system and compressed air system.
[0084] Open the purge valve to purge the hot primary air duct. After purging, put the micro oil ignition device into the ignition and control the primary air duct wall temperature at the preset first temperature threshold. At the same time, the air preheater performs soot blowing by the sonic soot blower.
[0085] When the outlet temperature of the coal mill separator reaches the preset second temperature threshold, the coal mill is started to introduce pulverized coal into the air duct, thereby igniting the boiler.
[0086] For example, the preset third pressure threshold is 7 kPa, the preset first pressure range is 1.8-2.0 MPa, and the preset second temperature threshold is 420°C.
[0087] In the above scheme, the acoustic soot blower only requires compressed air from the plant and does not require auxiliary steam, thus achieving the goal of saving auxiliary steam and ensuring the safe operation of the air preheater.
[0088] As a preferred embodiment, step S3, after successful boiler ignition, involves heating and pressurizing the main steam and reheat steam of the boiler, including:
[0089] After the boiler is successfully ignited, open the boiler EBV valve, open the boiler 5% start-up drain, open the boiler superheater and reheater vent valves, and at the same time keep the turbine side drain closed to heat up and pressurize the main steam of the boiler.
[0090] Open the high-pressure bypass valve, and the main steam and the reheat steam after being depressurized by the high-pressure bypass valve are connected to the cold reheat pipeline to form reheat steam;
[0091] Close the high-pressure bypass spray desuperheating water shut-off valve, open the high-pressure drain check valve and drain water to the trench drain valve, check and open the electric and manual doors of the cold reheat supply high auxiliary manifold to introduce reheat steam into the high auxiliary manifold.
[0092] Open the manual drain valve to warm up the pipes and increase the temperature and pressure of the boiler's reheat steam.
[0093] It should be noted that, during the steam circulation pressurization stage of this embodiment of the invention, the pneumatic drain valves of the main steam pipeline, the pneumatic drain valves of the pipeline before the main steam valve, the pneumatic drain valves of the main steam valve, the pneumatic drain valves after the main steam valve, the pneumatic drain valves of the pipeline before the high-pressure exhaust check valve, the pneumatic drain valves of the pipeline after the high-pressure exhaust check valve, the pneumatic drain valves of the pipeline before and after the low-pressure bypass electric valve, the pneumatic drain valves of the low-pressure bypass valve, and the pneumatic drain valves of the pipeline before and after the medium-pressure main steam valve and the valve seat are kept closed; the drain valves of the turbine cylinder body and the drain valves of the extraction steam pipeline are kept closed; and the electric and manual valves of the main steam pipeline to the shaft seal are kept closed.
[0094] As a preferred embodiment, step S4, when the pressure of the reheat steam reaches a preset first pressure threshold, supplies steam to the shaft sealing system for pipe warming. Steam is supplied to the shaft sealing system through the high-voltage auxiliary header to form a first self-steam supply closed loop, including:
[0095] When the main steam pressure reaches the preset fourth pressure threshold, close the boiler-side vent valve;
[0096] When the reheat steam pressure reaches the preset fifth pressure threshold, close the manual valve of the drain ditch after the high-pressure non-return valve, and close the drain valves of each drain ditch slightly.
[0097] When the steam drum pressure reaches the preset sixth pressure threshold, the boiler 5% bypass drain is shut off; when the steam drum pressure reaches the preset seventh pressure threshold, the EBV valve is shut off.
[0098] When the reheat steam pressure reaches the preset first pressure threshold, steam is supplied to the shaft seal system through the cold reheat shaft seal electric valve to warm the pipes. The drainage of each filter screen in the shaft seal system is checked locally to ensure that steam is supplied to the shaft seal system, thus forming the first self-steam closed loop.
[0099] For example, the preset fourth pressure threshold is 0.15 MPa, the preset fifth pressure threshold is 0.25 MPa, the preset sixth pressure threshold is 0.5 MPa, the preset seventh pressure threshold is 3.5 MPa, and the preset first pressure threshold is 0.5 MPa.
[0100] Furthermore, preferably, when supplying steam to the shaft seal system, if the shaft seal steam supply temperature is lower than a preset third temperature threshold, the shaft seal steam supply main pipe electric heater is activated, and the heater is activated or deactivated according to the shaft seal steam supply temperature.
[0101] It should be noted that, in principle, the temperature difference between the shaft seal steam supply temperature and the high and intermediate pressure cylinder exhaust metal temperature should be controlled to be less than 150℃. When the temperature difference is not less than 150℃, the turning gear time should be shortened as much as possible. The requirements for the turbine shaft seal steam supply temperature are as follows: if the turbine first-stage outer wall metal temperature is <150℃, the shaft seal steam supply temperature range is 150-260℃; if the turbine first-stage outer wall metal temperature is >150℃, the shaft seal steam supply temperature range is 208-375℃.
[0102] Therefore, in this embodiment of the invention, if the shaft seal steam supply temperature is low, an electric heater for the shaft seal steam supply header can be activated. Multiple electric heaters are connected in parallel to the shaft seal steam supply header, and the heaters are activated and deactivated according to the temperature. The shaft seal steam supply temperature is increased by electric heating so that the shaft seal temperature corresponds to the turbine metal temperature, thus meeting the start-up requirements.
[0103] As a preferred embodiment, step S5, when the pressure of the main steam reaches a preset second pressure threshold, performs condensate warming of the shaft seal system and the small turbine shaft seal system, and simultaneously adjusts the main steam pipeline to directly connect the main steam to the turbine shaft seal system, forming a second self-steam closed loop, including:
[0104] When the pressure of the main steam reaches the preset second pressure threshold, the shaft seal system drain warming and the small turbine shaft seal system drain warming are performed.
[0105] Open the manual and electric valves of the main steam supply shaft seal steam source, slightly open the main steam supply shaft seal steam inlet adjustment valve, and open the drain from the main steam pipeline to the shaft seal. During the draining process, keep the condenser body's expansion spray continuously open so that the main steam can be directly connected to the turbine shaft seal system, forming a second self-supply closed loop.
[0106] For example, the preset second pressure threshold is 1.0 MPa.
[0107] In a preferred embodiment, step S6 involves supplying steam to the gas turbine unit shaft seal through the first self-steam closed loop and the second self-steam closed loop. When the shaft seal is in normal operation, a vacuuming operation is performed, and the bypass system is activated, including:
[0108] Steam is supplied to the shaft seals of the gas turbine unit through the first self-steam supply closed loop and the second self-steam supply closed loop to ensure normal pressure;
[0109] Once the shaft sealing system is in normal operation, perform a vacuuming operation.
[0110] When the unit vacuum reaches the preset first pressure threshold, open all drains from the unit to the condenser and open the drains before and after the low-pressure bypass electric valve.
[0111] When the unit vacuum reaches the preset second pressure threshold, the low-pressure bypass electric main valve is slowly opened, and the low-pressure bypass valves on sides A and B are opened by 5%, thus activating the bypass system; the second pressure threshold is greater than the first pressure threshold.
[0112] For example, the preset first pressure threshold is 20 kPa, and the preset second pressure threshold is 70 kPa.
[0113] In a preferred implementation, after step S7 and the bypass system are put into operation, the boiler is heated and pressurized, and the small turbine is started up and warmed up through the high-voltage auxiliary header to achieve turbine start-up, including:
[0114] After the bypass system is put into operation, the boiler is heated and pressurized, and all vent and drain valves on the furnace side are checked and confirmed to be closed.
[0115] When the pressure of the high-pressure auxiliary manifold reaches the preset eighth pressure threshold, the blower heater and boiler are put into operation for continuous soot blowing in the air preheater.
[0116] Based on the steam source of the high-auxiliary header, the small turbine is started and warmed up;
[0117] Adjust the turbine startup parameters according to the startup conditions, and then start the turbine startup.
[0118] For example, the preset eighth pressure threshold is 0.6 MPa.
[0119] It should be noted that before and after turbine cylinder cut-off, attention should be paid to the impact of the drop in cold repressure on each user, such as observing whether the high-level auxiliary header and the small turbine steam source are operating normally.
[0120] As a preferred embodiment, step S8, when the primary hot air temperature at the air preheater outlet is greater than a preset air temperature threshold, involves disengaging the micro-oil ignition device to complete the cold start-up of the coal-fired unit, including:
[0121] When the primary hot air temperature at the air preheater outlet exceeds the preset air temperature threshold, the micro-oil ignition device is deactivated.
[0122] Start the primary air fan on the side where the non-oil ignition device is installed in the hot primary air duct to balance the output of the primary air fans on both sides and complete the cold start of the coal-fired unit.
[0123] Perform grid connection operations for coal-fired power units.
[0124] For example, the preset wind temperature threshold is 160°C.
[0125] Please see Figure 3 , Figure 3 A schematic diagram of a boiler used in an embodiment of the present invention is provided.
[0126] For example, when performing a cold start-up of a coal-fired unit, the following steps should be followed.
[0127] The micro-oil ignition device in the flue gas duct of the boiler is installed on one side of the hot primary air duct. After taking measures to prevent the primary air fan on the other side from reversing, the boiler is purged.
[0128] Fill the boiler with water. After the boiler is full, start the boiler water circulation pump and the flue gas system to purge the furnace. After the boiler purging is complete, close the primary air connection damper and start the primary air fan on the oil ignition side, keeping the outlet damper of the other primary air fan and its corresponding air preheater outlet damper closed. After increasing the primary air header pressure to 7 kPa, open the start-up mill outlet damper, the start-up mill primary air shut-off damper, and the hot air damper. Open the mill bypass damper to 50% for mill warm-up. Maintain the fuel oil pressure at 1.8–2.0 MPa. a. Open the manual valves of the furnace air duct micro-oil ignition fuel system and compressed air system; open the purging valve to purge the air duct micro-oil ignition system. After purging, put one air duct micro-oil ignition system into operation to ignite the micro-oil ignition system. Control the primary air duct wall temperature at about 420°C. At the same time, the air preheater uses the sonic soot blower to blow soot. The sonic soot blower only requires compressed air from the plant and does not require auxiliary steam, thus saving auxiliary steam and ensuring the safe operation of the air preheater. Once the coal mill separator outlet temperature reaches 65°C and the start-up conditions are met, start the coal mill.
[0129] After the boiler is successfully ignited, open the boiler EBV valve, open the boiler 5% start-up drain, and open the boiler superheater and reheater vent valves to heat up and pressurize the boiler. During the boiler heating and pressurization process, the boiler circulates and pressurizes the primary steam (i.e., main steam) system, while the turbine-side drain valves remain closed. Simultaneously, the following pneumatic drain valves are kept closed: main steam pipeline pneumatic drain valve 1, main steam valve inlet pneumatic drain valve 2, main steam valve drain valves 3 and 4, main steam valve outlet pneumatic drain valve 5, high-pressure exhaust check valve inlet pneumatic drain valves 6 and 7, high-pressure exhaust check valve outlet pneumatic drain valve 8, low-pressure bypass electric valve inlet and outlet pneumatic drain valves 10, low-pressure bypass valve outlet pneumatic drain valve 11, and medium-pressure main steam valve inlet and valve seat pneumatic drain valves 9, 12, and 13. The turbine cylinder body drain valves and extraction steam pipeline drain valves are also kept closed. The main steam pipeline to shaft seal electric and manual valves 14 and 15 are also kept closed. The boiler secondary steam (i.e. reheat steam) system begins to heat up and pressurize. Open the high-pressure bypass valve 16 to 10% opening, close the high-pressure bypass spray desuperheating water shut-off valve, open the high-pressure exhaust check valve and drain 8 to the drainage ditch drain valve, check and open the electric door 17 and manual door 18 of the cold reheat supply high-pressure auxiliary manifold, and open the drain manual door to warm up the pipes.
[0130] When the main steam pressure reaches 0.15 MPa, close the boiler-side vent valve. When the cold reheat pressure rises to 0.25 MPa, promptly close the manual valve of the drain ditch after the high-pressure exhaust check valve, and partially close the drain ditch valves of the aforementioned drains to prevent a large amount of steam from escaping. When the steam drum pressure reaches 0.5 MPa, close the boiler 5% bypass drain; when the steam drum pressure reaches 3.5 MPa, close the EBV. After the boiler secondary steam system reaches the required pressure, engage the turbine shaft seal system. When the cold reheat pressure reaches 0.5 MPa, supply steam to the shaft seal system for warming the pipes through the cold reheat shaft seal electric valve 19, and check on-site that the drains from each filter screen of the shaft seal system are unobstructed, forming the first self-steam closed loop.
[0131] When the main steam pressure reaches 1.0 MPa, open the manual valve 14 and electric valve 15 of the main steam supply shaft seal steam source, slightly open the main steam supply shaft seal steam inlet regulating valve 22, open the main steam pipeline to the shaft seal drain, and at the same time carry out the shaft seal system drain warming and the small turbine shaft seal system drain warming. During the draining period, keep the condenser body drain spray continuously open, thus forming the second self-steam supply closed loop.
[0132] The unit's shaft seal is supplied by both cold reheat and main steam sources to ensure normal pressure. After the shaft seal system is put into normal operation, a vacuuming operation is performed. Once the unit vacuum is >20 kPa, open drain valves 1-8 from the unit to the condenser, and open drain valves 9-13 before and after the low-pressure bypass electric valve. Once the unit vacuum is >70 kPa, slowly open the low-pressure bypass electric main valve 20 and the A and B side low-pressure bypass valves 21 to a 5% opening degree to engage the bypass system. Pay attention to the vibration of the bypass system pipelines, measure the temperature of each drain pipeline, and ensure unobstructed drainage.
[0133] After the bypass system is put into operation, the boiler is heated and pressurized, and all vent and drain valves on the boiler side are checked and confirmed to be closed. With the high-pressure auxiliary steam header pressure > 0.6 MPa, the blower heater is activated, and the boiler undergoes continuous soot blowing in the air preheater. If the high-pressure auxiliary steam source is sufficient, one small turbine can be started up and warmed up. Adjustments are made according to the turbine start-up parameters, and once the start-up conditions are met, the turbine is started up.
[0134] Before and after turbine cylinder cut-off, pay attention to the impact of the cold repressure drop on the steam source of various users such as high-voltage auxiliary turbines and small turbines. Before the unit is connected to the grid, check the hot primary air temperature at the air preheater outlet. When the hot primary air temperature at the air preheater outlet is greater than 160°C, remove the oil ignition gun in the air duct and start the primary air fan on the shut-down side to balance the output of the primary air fans on both sides. The remaining steps are performed according to the normal start-up procedure.
[0135] This invention provides a cold-start method for coal-fired power units without auxiliary steam source. A micro-oil ignition device installed in the boiler's hot primary air duct meets the separator outlet temperature requirements for pulverizer ignition, solving the problem of air preheater steam blowing being impossible without steam. After unit ignition and startup, self-generated steam restores the auxiliary steam and shaft seal system to normal operation, forming a dual self-steam supply for rapid unit startup. The turbine shaft seal vacuuming operation is then gradually initiated. As the hot primary air temperature gradually rises, the micro-oil ignition device is deactivated. Once the unit reaches the start-up conditions, the turbine is started up and the generator is connected to the grid. This invention is applicable to the fully cold-start of coal-fired power units without a start-up boiler, boiler oil burner and associated fuel oil tank, and temporary auxiliary steam, effectively shortening startup time and saving startup costs.
[0136] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.
[0137] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.
Claims
1. A cold start method for a coal-fired power unit without an auxiliary steam source, characterized in that, include: Install a micro-oil ignition device on one side of the hot primary air duct of the boiler in the coal-fired unit; The micro-oil ignition device is activated to ignite the pulverized coal in the hot primary air duct using fuel oil and compressed air, thus achieving boiler ignition. After the boiler is successfully ignited, the main steam and reheat steam of the boiler are heated and pressurized; the reheat steam is depressurized by the high-pressure bypass valve and then connected to the cold reheat pipeline and introduced into the high-pressure auxiliary manifold. When the pressure of the reheat steam reaches the preset first pressure threshold, steam is supplied to the shaft seal system to warm the pipes. Steam is supplied to the shaft seal system through the high auxiliary header to form the first self-steam closed loop. When the pressure of the main steam reaches the preset second pressure threshold, the shaft seal system drain warming and the small turbine shaft seal system drain warming are performed. At the same time, the main steam pipeline is adjusted to directly connect the main steam to the turbine shaft seal system, forming a second self-steam closed loop. Steam is supplied to the gas turbine unit shaft seal through the first self-steam supply closed loop and the second self-steam supply closed loop. When the shaft seal is in normal operation, a vacuuming operation is performed and the bypass system is activated. After the bypass system is put into operation, the boiler is heated and pressurized, and the small turbine is started up and warmed up through the high-voltage auxiliary header to realize the turbine start-up; When the primary air temperature at the air preheater outlet exceeds the preset air temperature threshold, the micro-oil ignition device is deactivated, completing the cold start of the coal-fired unit.
2. The cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, The micro-oil ignition device includes an oil and gas supply module, a burner module, and a DCS control module. The oil and gas supply module provides fuel and oxygen required for combustion to the burner module; the burner module includes an ignition gun and two atomizing micro-oil guns, with one atomizing micro-oil gun in operation and the other in standby mode; the DCS control module controls the opening and closing of the micro-oil ignition device.
3. The cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, The step of activating the micro-oil ignition device to ignite pulverized coal in the hot primary air duct using fuel oil and compressed air to achieve boiler ignition includes: After taking measures to prevent the fan on the side where the non-oil ignition device is installed in the hot primary air duct from reversing, the boiler is purged. Fill the boiler with water. After the boiler is full of water, start the boiler water circulation pump and start the flue gas system to purge the furnace. After the furnace is purged, close the primary air connection damper and start the primary air fan on the side where the micro oil ignition device is installed. At the same time, keep the primary air fan outlet damper and its corresponding air preheater outlet damper on the side where the non-micro oil ignition device is installed closed. When the pressure of the primary air main pipe increases to the preset third pressure threshold, the start-up mill outlet damper, the start-up mill primary air shut-off damper and the hot air damper are opened, and the mill bypass damper is opened to 50% to warm up the mill. Maintain the fuel pressure within the preset first pressure range, and open the manual valves of the furnace air duct micro-oil ignition fuel system and compressed air system. Open the purge valve to purge the hot primary air duct. After purging, put the micro oil ignition device into the ignition and control the primary air duct wall temperature at the preset first temperature threshold. At the same time, the air preheater performs soot blowing by the sonic soot blower. When the outlet temperature of the coal mill separator reaches the preset second temperature threshold, the coal mill is started to introduce pulverized coal into the air duct, thereby igniting the boiler.
4. The cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, After successful boiler ignition, the main steam and reheat steam of the boiler are heated and pressurized; the reheat steam is depressurized by a high-pressure bypass valve and then connected to a cold reheat pipeline, and introduced into a high-pressure auxiliary manifold, including: After the boiler is successfully ignited, open the boiler EBV valve, open the boiler 5% start-up drain, open the boiler superheater and reheater vent valves, and at the same time keep the turbine side drain closed to heat up and pressurize the main steam of the boiler. Open the high-pressure bypass valve, and the main steam and the reheat steam after being depressurized by the high-pressure bypass valve are connected to the cold reheat pipeline to form reheat steam; Close the high-pressure bypass spray desuperheating water shut-off valve, open the high-pressure drain check valve and drain water to the trench drain valve, check and open the electric and manual doors of the cold reheat supply high auxiliary manifold to introduce reheat steam into the high auxiliary manifold. Open the manual drain valve to warm up the pipes and increase the temperature and pressure of the boiler's reheat steam.
5. The cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, When the pressure of the reheat steam reaches a preset first pressure threshold, steam is supplied to the shaft sealing system to warm the pipes. Steam is supplied to the shaft sealing system through the high-voltage auxiliary header, forming a first self-steam supply closed loop, including: When the main steam pressure reaches the preset fourth pressure threshold, close the boiler-side vent valve; When the reheat steam pressure reaches the preset fifth pressure threshold, close the manual valve of the drain ditch after the high-pressure non-return valve, and close the drain valves of each drain ditch slightly. When the steam drum pressure reaches the preset sixth pressure threshold, the boiler 5% bypass drain is shut off; when the steam drum pressure reaches the preset seventh pressure threshold, the EBV valve is shut off. When the reheat steam pressure reaches the preset first pressure threshold, steam is supplied to the shaft seal system through the cold reheat shaft seal electric valve to warm the pipes. The drainage of each filter screen in the shaft seal system is checked locally to ensure that steam is supplied to the shaft seal system, thus forming the first self-steam closed loop.
6. A cold start method for a coal-fired power unit without an auxiliary steam source as described in claim 1 or 5, characterized in that, When supplying steam to the shaft seal system, if the shaft seal steam supply temperature is lower than the preset third temperature threshold, the shaft seal steam supply main pipe electric heater is activated, and the heater is activated and deactivated according to the shaft seal steam supply temperature.
7. The cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, When the pressure of the main steam reaches a preset second pressure threshold, the shaft seal system drain pipe warming and the small turbine shaft seal system drain pipe warming are performed. Simultaneously, the main steam pipeline is adjusted to directly connect the main steam to the turbine shaft seal system, forming a second self-supplied steam closed loop, including: When the pressure of the main steam reaches the preset second pressure threshold, the shaft seal system drain warming and the small turbine shaft seal system drain warming are performed. Open the manual and electric valves of the main steam supply shaft seal steam source, slightly open the main steam supply shaft seal steam inlet adjustment valve, and open the drain from the main steam pipeline to the shaft seal. During the draining process, keep the condenser body's expansion spray continuously open so that the main steam can be directly connected to the turbine shaft seal system, forming a second self-supply closed loop.
8. The cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, The process of supplying steam to the gas turbine unit shaft seals through the first and second self-steam supply closed loops, and performing a vacuuming operation and activating the bypass system when the shaft seals are in normal operation, includes: Steam is supplied to the shaft seals of the gas turbine unit through the first self-steam supply closed loop and the second self-steam supply closed loop to ensure normal pressure; Once the shaft sealing system is in normal operation, perform a vacuuming operation. When the unit vacuum reaches the preset first pressure threshold, open all drains from the unit to the condenser and open the drains before and after the low-pressure bypass electric valve. When the unit vacuum reaches the preset second pressure threshold, the low-pressure bypass electric main valve is slowly opened, and the low-pressure bypass valves on sides A and B are opened by 5%, thus activating the bypass system; the second pressure threshold is greater than the first pressure threshold.
9. A cold start method for a coal-fired unit without an auxiliary steam source as described in claim 1, characterized in that, After the bypass system is put into operation, the boiler is heated and pressurized, and the small turbine is started up and warmed up through the high-voltage auxiliary header to achieve turbine start-up, including: After the bypass system is put into operation, the boiler is heated and pressurized, and all vent and drain valves on the furnace side are checked and confirmed to be closed. When the pressure of the high-pressure auxiliary manifold reaches the preset eighth pressure threshold, the blower heater and boiler are activated to continuously blow soot in the air preheater. Based on the steam source of the high-auxiliary header, the small turbine is started and warmed up; Adjust the turbine startup parameters according to the startup conditions, and then start the turbine startup.
10. A cold start method for a coal-fired power unit without an auxiliary steam source as described in claim 1, characterized in that, When the primary air temperature at the air preheater outlet exceeds a preset air temperature threshold, the micro-oil ignition device is deactivated, completing the cold start-up of the coal-fired unit, including: When the primary hot air temperature at the air preheater outlet exceeds the preset air temperature threshold, the micro-oil ignition device is deactivated. Start the primary air fan on the side where the non-oil ignition device is installed in the hot primary air duct to balance the output of the primary air fans on both sides and complete the cold start of the coal-fired unit. Perform grid connection operations for coal-fired power units.