Application and Trend of Energy-saving Optimization Technology in Thermal Power Plants
I. INTRODUCTION The state has vigorously advocated the path of conservation-oriented development and cherished resources, energy conservation, environmental protection, and sustainable development. Leaders at all levels of Huaneng Group Corporation attach great importance to energy conservation and environmental protection work, and actively participate in the infiltration and practice of saving ideas at work, and implement the “saving of the whole people and joint action†approach to conservation. Huaneng has created the first number of energy saving and environmental protection projects in providing clean energy products, the operation of the first ultra-supercritical thermal power generating unit in China, the construction and operation of the first 600,000 and 1 million thermal power generating units in China, and the first in China. The operation of a 30KW photovoltaic grid-connected power generation system, and the promotion of the use of renewable energy such as wind power generation. Since coal-fired power plants are still the mainstay, how to implement and implement these principles and policies in thermal power plants to vigorously promote energy-saving in thermal power plants is a problem worthy of discussion, and the promotion and application of new technologies, new processes, and new management It is the only way to achieve energy savings. The following is a preliminary discussion of the actual production process of the power plant, combined with the experience of the implementation of energy-saving projects, in order to seek to attract bricks and jade.
II. The development of principle information, communication, computer, intelligent control and frequency conversion technology has provided unprecedented means for the efficient, economical operation, scientific management, and process optimization of thermal power plants, which in turn promotes the scientific management and automation of thermal power plants. The improvement.
For energy-saving projects must seek a reasonable rate of return on investment, power plant energy-saving projects can not be large and complete, blindly seeking new reality; the guiding principles of power plant energy-saving projects are as follows: "benefit-based", "sub-item implementation", "technology "Updates" and "key breakthroughs" are combined with each other. Strive for projects that can achieve good economic and social benefits, and implement more independent and operational.
Third, the current status of energy-saving engineering practices in thermal power plants:
At the beginning of its establishment, Huaneng Group Corporation paid enough attention to energy conservation, closely focused on the safe production and operation of power generation products, energy conservation, consumption reduction, environmental protection optimization, cost reduction, sustainable development, and improvement of comprehensive economic and social benefits as the focus of work. Through the implementation of energy-saving project special projects, the introduction of various advanced technologies and management experience, exploring and practicing various ways of saving, gained experience, cultivated talents, promoted the improvement of safety production level, and made reserves for future energy conservation work. Get good results in the following projects:
3.1 Boiler Combustion Optimization Control System Relying on Huaneng Automation Engineering Co., Ltd. in Huaneng Yangliuqing Power Plant to implement special support for energy-saving reform of boiler combustion optimization system, and promote the application of intelligent optimization technology. Optimization of the system contains expert software technology, energy-saving effect is very obvious, the formal test by the Northeast Electric Power Research Institute, the boiler efficiency increased by 0.5% to 0.7%, send and draw fan power consumption reduced by 287KW-823KW, nitrogen oxide emissions decreased From 15.3% to 26.7%, the amount of desuperheater water for reheaters has been greatly reduced, which has improved the unit's thermal efficiency.
The optimized control system analyzes the following parameters of the DCS system: primary air temperature, air flow, secondary air temperature, air flow rate, flue gas discharge temperature, powder feeder feed flow rate, reheater temperature, superheater temperature, furnace outlet excess air ratio; And furnace negative pressure, furnace flue gas temperature, air preheater flue gas inlet temperature, pulverized coal pulverized coal temperature, superheater pressure, reheater pressure, superheater spray volume, reheater spray volume, unit power , Auxiliary power consumption, etc. to achieve optimal control of boiler combustion.
Optimize the closed-loop control of the control system to increase the thermal efficiency of the boiler, reduce the fuel loss from ignition, and reduce the emission of pollutants such as nitrogen oxides and carbon monoxide. It has significant economic benefits and social environmental benefits; the investment of the project is relatively small, and it is not necessary to change the equipment at the site, and does not substantially affect the normal operation of the unit. The implementation risk is low and the investment return period is short. After system optimization and control, if the thermal efficiency of the boiler is increased by 1%, a unit of 300,000 units is estimated to have a coal consumption of 370 grams per kWh of power generation, and will run for 6,000 hours a year, saving 6,660 tons of coal and 200 yuan per ton of coal. According to the calculation, the direct economic benefit that can be obtained within one year is 1.332 million yuan.
3.2 Real-time production supervision system Relying on the special support of the production real-time supervision system of all power plants of the company implemented by Huaneng Information Industry Company, the company's supervision of the power plant is strengthened, which helps the company's leaders to make a reasonable business strategy and saves many operating costs.
3.3 High-low voltage variable frequency speed control system relying on Huaneng Automation Engineering Company to implement 380V low voltage variable frequency speed control system (powder pump, powder feeder, coal feeder, etc.) in Huaneng Weihai Power Plant, Haikou Power Plant, and Changxing Power Plant to explore the low voltage variable frequency speed control system Application; Special support for frequency conversion and energy saving reform of condensate water system in Huaiyin Power Plant; exploration of the application of frequency conversion control system for mechatronics; transformation plan: change the condensate pump to inverter control and control the speed of the inverter in DCS Realize, DCS carries on the normal adjustment according to the deaerator, condenser water level, controls the condensing water pump rotational speed, reduces the pressure loss of the condensed water system, achieves the purpose of saving the electricity consumption of the condensate pump factory. After the transformation, the frequency conversion adjustment system configuration is as shown in the figure:
Relying on Huaneng Automation Engineering Co., Ltd. in the Huaneng Xinhua, Yushe power plant to implement high-voltage large-capacity frequency conversion energy-saving transformation of special support, to explore the application of high-voltage large-capacity frequency control system. The formation of three kinds of high voltage motor frequency control program.
According to our engineering practice in recent years, such as Huaneng Xinhua Power Plant's feed water pump put into operation 5 sets, Huaneng Power Plant's induced draft fan 2 sets, Huaneng Xindian Power Plant's water source booster pump put into operation 2 sets, Huaneng Huaiyin Two sets of condensate pumps in the power plant, the reliability of the frequency conversion speed control system can fully meet the requirements of the power generation companies, and the comprehensive operation efficiency is high. The energy saving effect is very significant, which is 30-50%. The transformation of motor frequency conversion speed regulation is one of the effective ways to save energy and reduce consumption of power plants. Should increase the technical transformation of energy-saving projects in this area.
3.4 Electrostatic Precipitation Optimization System Relying on Huaneng Automation Engineering Co., Ltd. in the Huaneng Weihai, Xindian, and Haikou Power Plants to implement special support for optimizing the energy-saving of electric dedusting, and to explore and promote the application of intelligent optimization control technology. This electrostatic precipitator control system is used as a complete tool to use it to provide high-precision, high-speed waveform analysis of primary and secondary currents and voltages of rectifier transformers (T/R), as well as new embedded expert intelligent software systems. ESP control technology. The system integrates the control of the high voltage partial thyristor and the control of the low pressure partial rapping in the same controller, thereby realizing the reduced power control rapping function. The rapping effect is obviously improved and the cleaning effect is obvious.
Man-machine communication and coordinated control are realized by field bus. Even if one electric field unit is completely faulty, the subordinate (downstream) software of the failed electric field will detect the change of the ESP operating condition and will immediately adjust (optimize) the corresponding operating parameter.
Advantages of the system: The optimization software for the power supply of the electrostatic precipitator is included. The software adopts the interval charging method to adjust the charge ratio in real time according to the operating conditions of the electrostatic precipitator (dust concentration, characteristics, flow rate of the flue gas, temperature, humidity, etc.) And charging current, reducing the generation of anti-corona, to achieve the best dust removal efficiency. Including emission optimization software, turbidity optimization software, and reduced-power rapping optimization software.
From the perspective of engineering operation practice, the energy-saving and environmental-protective effects of the electrostatic precipitator optimization system are significant. Under the same operating conditions of the boiler, the dust removal efficiency is increased by 0.3-0.7% over the design value, and the power consumption is reduced by about 20%. In order to meet more and more high environmental protection requirements, the technological transformation of electric dust control should be increased.
IV. Program Recommendations The implementation of these special projects for energy-saving engineering reform has initially formed a relatively reasonable energy-saving engineering technology program. In order to establish a conservation-oriented society and implement the policy of “green coal and electricity†in resource development and conservation, it is recommended that mature energy conservation programs be turned into practical actions to realize leap-forward development and achieve effective transformation of economic growth modes.
1. Power plant auxiliary control system networking, as well as integrated operation of DCS and auxiliary program control system.
2. The use of carrier, wireless communication, frequency control technology to achieve far-away energy saving control of the coal feeder of the coal conveying system impeller.
3. The use of information-based communications, frequency control technology to achieve unattended remote control of the energy cycle of the water system.
4. The use of information technology to achieve water source submersible pump and booster pump system unattended remote control.
5. Although the above-mentioned outlook has achieved the above results, due to modern technology being a highly integrated and rapidly developing technology, its R&D, transformation of results, and promotion and application are those that require a large investment and long-term sustained investment, and in the course of practical application must be due to technology. There are bound to be some problems with constraints such as reserves, personnel training, and use experience. Therefore, it is necessary to analyze and determine the rate of investment reporting, make full use of the favorable resources of all parties, and do a good job in energy conservation. In order to make better use of the company’s resource advantages, and firmly establish and earnestly implement the scientific concept of development, the company’s leadership (Dean Xizhi Zhi) requested Huaneng Automation Engineering Company to do a special survey and situation on the application of high-voltage inverters in the past two years. Report, and then use the technical characteristics of variable frequency energy-efficient, according to the development and use of high-voltage large-capacity frequency control technology, scope of application and problems in the use of the process, ready to implement new special technologies in high-voltage and large-capacity frequency conversion energy-saving work Support, and then vigorously promote the promotion of frequency conversion energy-saving projects, and promote the Huaneng company to take the lead in the establishment of a conservation-oriented society.
According to the technological development trend and situation, as well as the higher requirements of power plants for safe production, and the need to take the road of energy conservation and consumption reduction, the following aspects will continue to be carried out in the future: 1. Research on closed-loop optimal regulation and control of carbon in fly ash The implementation scheme of the special support system for energy saving projects is as follows:
The system collects the following data: unit power rating, unit actual power generation, smoke exhaust temperature, supply air temperature, fly ash carbon content, secondary and tertiary air baffle opening, secondary air flow, and feed speed.
2. The optimization of the air preheater
Mainly solve air leakage problem of air preheater and form low-leakage system Air leakage in air preheater is mainly caused by the following factors: (1) Heat distortion of rotor causes clearance between rotor and sector plate (2) Air side There is a pressure difference with the flue gas side (3) Entrainment air leakage from the rotor to 300,000 kW (300 MW) units: Conventional rotor seals (regulating sector and axial plates) <8%
Low-leakage rotor seals <6% (4.9%) Low-leakage system promotes energy-saving heat fin upgrades Improve thermal efficiency Solve jams and clogging problems 3. Intelligent optimization control of circulating water systems 4. Smart optimization of sootblowers Control 5. Intelligent optimization control of feedwater heater and steam cycle 6. Smart optimization control of ash removal and ash removal 7. Intelligent optimization control of short-term load forecasting 8. Smart optimization control of steam turbine 6. Experience summary 1) Since technological innovation is The result of fusion, symbiosis and mutual penetration of various technologies requires specialized companies and professionals to implement it to make up for the shortage of technical reserves of power plant technicians. The implementation of energy-saving engineering projects can not only train the technical personnel of professional companies, and then be quickly promoted to the next power plant, but the technical personnel of this power plant may not have been exposed to this knowledge. For example, after the practice of variable-frequency energy-saving engineering, the professional and technical personnel of professional companies have accumulated a lot of experience, and many problems such as harmonics, motor heating, power factor at low rotational speeds, and maintenance troubles occur in the application of high-voltage power frequency conversion devices. Find a better solution.
2). It is necessary to carry out a comprehensive summary of the energy conservation project special projects that have already been implemented, to identify problems and solve problems, and then to form relatively complete and perfect experiences, lessons, plans and standards, and then carry out training, organizational learning and training of high quality. Talents enable talents to accumulate experience from their studies, promote experience and technical solutions in their work, and implement energy conservation work.
3). Choosing the best way to implement the energy conservation work is very critical. The safety and reliability of the power plant are particularly important. The adoption of new technologies and new processes is a cautious attitude and often encounters resistance in the promotion. For example, boilers will be burned in Yangliuqing Power Plant. During the optimization of the system energy-saving special project, due to the requirement of the power plant operating personnel to change the original operation and operation habits, the operators at the initial stage of operation were very unwilling to do so, but after training and practical cooperation exercises and the improvement of personnel quality, the power plant operators are very fond of this set of equipment. The system reduces the coal consumption, reduces the number of operations and reduces the labor intensity.
4). Energy-saving work has strong practical significance. Adopting various energy-saving and consumption-reduction measures to reduce the plant electricity consumption rate of existing units and improve the output of existing units can partially relieve the shortage of electricity shortages and electricity shortages. situation.
II. The development of principle information, communication, computer, intelligent control and frequency conversion technology has provided unprecedented means for the efficient, economical operation, scientific management, and process optimization of thermal power plants, which in turn promotes the scientific management and automation of thermal power plants. The improvement.
For energy-saving projects must seek a reasonable rate of return on investment, power plant energy-saving projects can not be large and complete, blindly seeking new reality; the guiding principles of power plant energy-saving projects are as follows: "benefit-based", "sub-item implementation", "technology "Updates" and "key breakthroughs" are combined with each other. Strive for projects that can achieve good economic and social benefits, and implement more independent and operational.
Third, the current status of energy-saving engineering practices in thermal power plants:
At the beginning of its establishment, Huaneng Group Corporation paid enough attention to energy conservation, closely focused on the safe production and operation of power generation products, energy conservation, consumption reduction, environmental protection optimization, cost reduction, sustainable development, and improvement of comprehensive economic and social benefits as the focus of work. Through the implementation of energy-saving project special projects, the introduction of various advanced technologies and management experience, exploring and practicing various ways of saving, gained experience, cultivated talents, promoted the improvement of safety production level, and made reserves for future energy conservation work. Get good results in the following projects:
3.1 Boiler Combustion Optimization Control System Relying on Huaneng Automation Engineering Co., Ltd. in Huaneng Yangliuqing Power Plant to implement special support for energy-saving reform of boiler combustion optimization system, and promote the application of intelligent optimization technology. Optimization of the system contains expert software technology, energy-saving effect is very obvious, the formal test by the Northeast Electric Power Research Institute, the boiler efficiency increased by 0.5% to 0.7%, send and draw fan power consumption reduced by 287KW-823KW, nitrogen oxide emissions decreased From 15.3% to 26.7%, the amount of desuperheater water for reheaters has been greatly reduced, which has improved the unit's thermal efficiency.
The optimized control system analyzes the following parameters of the DCS system: primary air temperature, air flow, secondary air temperature, air flow rate, flue gas discharge temperature, powder feeder feed flow rate, reheater temperature, superheater temperature, furnace outlet excess air ratio; And furnace negative pressure, furnace flue gas temperature, air preheater flue gas inlet temperature, pulverized coal pulverized coal temperature, superheater pressure, reheater pressure, superheater spray volume, reheater spray volume, unit power , Auxiliary power consumption, etc. to achieve optimal control of boiler combustion.
Optimize the closed-loop control of the control system to increase the thermal efficiency of the boiler, reduce the fuel loss from ignition, and reduce the emission of pollutants such as nitrogen oxides and carbon monoxide. It has significant economic benefits and social environmental benefits; the investment of the project is relatively small, and it is not necessary to change the equipment at the site, and does not substantially affect the normal operation of the unit. The implementation risk is low and the investment return period is short. After system optimization and control, if the thermal efficiency of the boiler is increased by 1%, a unit of 300,000 units is estimated to have a coal consumption of 370 grams per kWh of power generation, and will run for 6,000 hours a year, saving 6,660 tons of coal and 200 yuan per ton of coal. According to the calculation, the direct economic benefit that can be obtained within one year is 1.332 million yuan.
3.2 Real-time production supervision system Relying on the special support of the production real-time supervision system of all power plants of the company implemented by Huaneng Information Industry Company, the company's supervision of the power plant is strengthened, which helps the company's leaders to make a reasonable business strategy and saves many operating costs.
3.3 High-low voltage variable frequency speed control system relying on Huaneng Automation Engineering Company to implement 380V low voltage variable frequency speed control system (powder pump, powder feeder, coal feeder, etc.) in Huaneng Weihai Power Plant, Haikou Power Plant, and Changxing Power Plant to explore the low voltage variable frequency speed control system Application; Special support for frequency conversion and energy saving reform of condensate water system in Huaiyin Power Plant; exploration of the application of frequency conversion control system for mechatronics; transformation plan: change the condensate pump to inverter control and control the speed of the inverter in DCS Realize, DCS carries on the normal adjustment according to the deaerator, condenser water level, controls the condensing water pump rotational speed, reduces the pressure loss of the condensed water system, achieves the purpose of saving the electricity consumption of the condensate pump factory. After the transformation, the frequency conversion adjustment system configuration is as shown in the figure:
Relying on Huaneng Automation Engineering Co., Ltd. in the Huaneng Xinhua, Yushe power plant to implement high-voltage large-capacity frequency conversion energy-saving transformation of special support, to explore the application of high-voltage large-capacity frequency control system. The formation of three kinds of high voltage motor frequency control program.
According to our engineering practice in recent years, such as Huaneng Xinhua Power Plant's feed water pump put into operation 5 sets, Huaneng Power Plant's induced draft fan 2 sets, Huaneng Xindian Power Plant's water source booster pump put into operation 2 sets, Huaneng Huaiyin Two sets of condensate pumps in the power plant, the reliability of the frequency conversion speed control system can fully meet the requirements of the power generation companies, and the comprehensive operation efficiency is high. The energy saving effect is very significant, which is 30-50%. The transformation of motor frequency conversion speed regulation is one of the effective ways to save energy and reduce consumption of power plants. Should increase the technical transformation of energy-saving projects in this area.
3.4 Electrostatic Precipitation Optimization System Relying on Huaneng Automation Engineering Co., Ltd. in the Huaneng Weihai, Xindian, and Haikou Power Plants to implement special support for optimizing the energy-saving of electric dedusting, and to explore and promote the application of intelligent optimization control technology. This electrostatic precipitator control system is used as a complete tool to use it to provide high-precision, high-speed waveform analysis of primary and secondary currents and voltages of rectifier transformers (T/R), as well as new embedded expert intelligent software systems. ESP control technology. The system integrates the control of the high voltage partial thyristor and the control of the low pressure partial rapping in the same controller, thereby realizing the reduced power control rapping function. The rapping effect is obviously improved and the cleaning effect is obvious.
Man-machine communication and coordinated control are realized by field bus. Even if one electric field unit is completely faulty, the subordinate (downstream) software of the failed electric field will detect the change of the ESP operating condition and will immediately adjust (optimize) the corresponding operating parameter.
Advantages of the system: The optimization software for the power supply of the electrostatic precipitator is included. The software adopts the interval charging method to adjust the charge ratio in real time according to the operating conditions of the electrostatic precipitator (dust concentration, characteristics, flow rate of the flue gas, temperature, humidity, etc.) And charging current, reducing the generation of anti-corona, to achieve the best dust removal efficiency. Including emission optimization software, turbidity optimization software, and reduced-power rapping optimization software.
From the perspective of engineering operation practice, the energy-saving and environmental-protective effects of the electrostatic precipitator optimization system are significant. Under the same operating conditions of the boiler, the dust removal efficiency is increased by 0.3-0.7% over the design value, and the power consumption is reduced by about 20%. In order to meet more and more high environmental protection requirements, the technological transformation of electric dust control should be increased.
IV. Program Recommendations The implementation of these special projects for energy-saving engineering reform has initially formed a relatively reasonable energy-saving engineering technology program. In order to establish a conservation-oriented society and implement the policy of “green coal and electricity†in resource development and conservation, it is recommended that mature energy conservation programs be turned into practical actions to realize leap-forward development and achieve effective transformation of economic growth modes.
1. Power plant auxiliary control system networking, as well as integrated operation of DCS and auxiliary program control system.
2. The use of carrier, wireless communication, frequency control technology to achieve far-away energy saving control of the coal feeder of the coal conveying system impeller.
3. The use of information-based communications, frequency control technology to achieve unattended remote control of the energy cycle of the water system.
4. The use of information technology to achieve water source submersible pump and booster pump system unattended remote control.
5. Although the above-mentioned outlook has achieved the above results, due to modern technology being a highly integrated and rapidly developing technology, its R&D, transformation of results, and promotion and application are those that require a large investment and long-term sustained investment, and in the course of practical application must be due to technology. There are bound to be some problems with constraints such as reserves, personnel training, and use experience. Therefore, it is necessary to analyze and determine the rate of investment reporting, make full use of the favorable resources of all parties, and do a good job in energy conservation. In order to make better use of the company’s resource advantages, and firmly establish and earnestly implement the scientific concept of development, the company’s leadership (Dean Xizhi Zhi) requested Huaneng Automation Engineering Company to do a special survey and situation on the application of high-voltage inverters in the past two years. Report, and then use the technical characteristics of variable frequency energy-efficient, according to the development and use of high-voltage large-capacity frequency control technology, scope of application and problems in the use of the process, ready to implement new special technologies in high-voltage and large-capacity frequency conversion energy-saving work Support, and then vigorously promote the promotion of frequency conversion energy-saving projects, and promote the Huaneng company to take the lead in the establishment of a conservation-oriented society.
According to the technological development trend and situation, as well as the higher requirements of power plants for safe production, and the need to take the road of energy conservation and consumption reduction, the following aspects will continue to be carried out in the future: 1. Research on closed-loop optimal regulation and control of carbon in fly ash The implementation scheme of the special support system for energy saving projects is as follows:
The system collects the following data: unit power rating, unit actual power generation, smoke exhaust temperature, supply air temperature, fly ash carbon content, secondary and tertiary air baffle opening, secondary air flow, and feed speed.
2. The optimization of the air preheater
Mainly solve air leakage problem of air preheater and form low-leakage system Air leakage in air preheater is mainly caused by the following factors: (1) Heat distortion of rotor causes clearance between rotor and sector plate (2) Air side There is a pressure difference with the flue gas side (3) Entrainment air leakage from the rotor to 300,000 kW (300 MW) units: Conventional rotor seals (regulating sector and axial plates) <8%
Low-leakage rotor seals <6% (4.9%) Low-leakage system promotes energy-saving heat fin upgrades Improve thermal efficiency Solve jams and clogging problems 3. Intelligent optimization control of circulating water systems 4. Smart optimization of sootblowers Control 5. Intelligent optimization control of feedwater heater and steam cycle 6. Smart optimization control of ash removal and ash removal 7. Intelligent optimization control of short-term load forecasting 8. Smart optimization control of steam turbine 6. Experience summary 1) Since technological innovation is The result of fusion, symbiosis and mutual penetration of various technologies requires specialized companies and professionals to implement it to make up for the shortage of technical reserves of power plant technicians. The implementation of energy-saving engineering projects can not only train the technical personnel of professional companies, and then be quickly promoted to the next power plant, but the technical personnel of this power plant may not have been exposed to this knowledge. For example, after the practice of variable-frequency energy-saving engineering, the professional and technical personnel of professional companies have accumulated a lot of experience, and many problems such as harmonics, motor heating, power factor at low rotational speeds, and maintenance troubles occur in the application of high-voltage power frequency conversion devices. Find a better solution.
2). It is necessary to carry out a comprehensive summary of the energy conservation project special projects that have already been implemented, to identify problems and solve problems, and then to form relatively complete and perfect experiences, lessons, plans and standards, and then carry out training, organizational learning and training of high quality. Talents enable talents to accumulate experience from their studies, promote experience and technical solutions in their work, and implement energy conservation work.
3). Choosing the best way to implement the energy conservation work is very critical. The safety and reliability of the power plant are particularly important. The adoption of new technologies and new processes is a cautious attitude and often encounters resistance in the promotion. For example, boilers will be burned in Yangliuqing Power Plant. During the optimization of the system energy-saving special project, due to the requirement of the power plant operating personnel to change the original operation and operation habits, the operators at the initial stage of operation were very unwilling to do so, but after training and practical cooperation exercises and the improvement of personnel quality, the power plant operators are very fond of this set of equipment. The system reduces the coal consumption, reduces the number of operations and reduces the labor intensity.
4). Energy-saving work has strong practical significance. Adopting various energy-saving and consumption-reduction measures to reduce the plant electricity consumption rate of existing units and improve the output of existing units can partially relieve the shortage of electricity shortages and electricity shortages. situation.
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