Latest ArticlesThe spot market of electricity makes electricity return to the commodity attribute, which makes the market play an increasingly prominent role in the allocation of power resources. The electricity-trading mode has become an important part of the power market construction and power reform because it is conducive to promoting the consumption of new energy power generation and realizing the optimal allocation of power resources. This paper constructs technical routes for a thermal power unit in Shandong Province. The first is waste heat recovery, refrigeration scheme based on the voltage shrink heat pump and the second is deep peak shaving scheme based on the electric boiler and energy storage tank. The technical transformation scheme is providefor the thermal power unit to participating in the spot power market. The result show that energy supply capacity of the system increased by 48 MW, the cooling capacity increased by 32 MW, and the peak shaving capacity of the unit increased by 9%. In addition, the financial internal rate of return (before tax) of the project is 30.25%, and the payback period (before tax) is 4.1 years, with good profitability.
The transformation of energy production to renewable energy is the only way to achieve the dual-carbon goal. At present, the lack of peak shaving capacity and flexibility of coal-fired units hinders the large-scale consumption of renewable energy. In this paper, taking a 600 MW coal-fired unit as the research object, eight schemes for peak shaving system aided by molten salt heat storage are proposed, and the peak shaving capacity and thermal performance of each scheme are compared and analyzed through simulation calculation. The results show that, the peak shaving system can improve the flexibility of coal-fired unit, effectively regulate the output, and greatly expand the operating range. Heating by electricity causes a large amount of exergy loss, while extracted exhaust of intermediate pressure cylinder causes a small amount of exergy loss. The maximum peak shaving capacity can be obtained by the scheme of heating the molten salt directly by electric energy output by generator when charging, and heating the bypass feedwater by high-temperature molten salt when discharging, whose peak shaving depth can reach 17.83%. Moreover, the highest system efficiency and economy can be obtained by the scheme of heating the molten salt with extracted exhaust of intermediate-pressure cylinder when charging, and heating the bypass feedwater with high-temperature molten salt when discharging, of which the system thermal efficiency and exergy efficiency are 40.95% and 40.29% respectively, and the coal consumption rate is 350.01 g/(kW·h).
A sludge pyrolysis system coupled with molten salt storage is an emerging novel thermal treatment technique for sludge disposal, which can simultaneously realize reduction and tar recovery by constructing rapid and homogeneous pyrolysis conditions. The effects of heating rate and calcium oxide (CaO) addition on the production characteristics of tar during sludge pyrolysis coupled with molten salt storage system were investigated via a high-precision optical wide heating rate pyrolysis apparatus. The results show that, the heating rate affected the tar yield at low pyrolysis temperatures. The tar yield increased by 14% at 350 ℃ when the heating rate increased from 60 ℃/min to 6 000 ℃/min. Meanwhile, the CaO addition could result in a sharp decrease in tar yield, an 39%~43% decrease could be observed with 10% CaO addition. Also, the CaO addition significantly affected the relative content of the compounds in tar, which was attributed to the fact that CaO could act as a catalyst and heat transfer retardant. The results are helpful to the pyrolysis condition regulation and high value-added tar obtain for the sludge pyrolysis system coupled with molten salt storage.
With the structural upgrading of China's energy industry and the transformation of economic growth mode, clean energy power generation technology has been continuously and rapidly developed. As a high-power electric heating conversion device, electric boiler has become one of the effective technical solutions to enhance the operational flexibility of thermal power units and promote the reliable consumption of new energy power. In this paper, the allocation and accounting principles of electric boiler capacity and heat storage capacity in such projects are proposed. The calculation model of system optimization operation parameters and operation economy evaluation is established based on the principle of maximizing the economic benefits of enterprises, taking into account the factors of grid peak shaving depth dispatching limits. Combined with the actual situation of the multi-unit system of a thermal power plant in Northeast China, the optimal configuration capacity of the electric boiler of the project is 300 MW, and the heat storage capacity is 17 MW·h. At the same time, the optimal operation scheme of the whole plant is proposed. The results show that, under the condition of 30% peak shaving depth limit, the case power plant can add about 139.53 million Yuan in each heating season, and the project investment payback period is about 5 years. In the foreseeable future, the project will have long-term profitability.
Based on the control difficulties in the operation process of the unit after the bypass heating alteration, a complete control strategy was proposed under the bypass heating condition, which realizes the bypass automatic control under the heating condition and meets the needs of the unit heating regulation at the same time. Aiming at the influence of bypass switching on and off and working condition disturbance on the operation stability of steam turbine under the heating condition, as well as the change of unit safety boundary, a set of logic design scheme including bypass blocking and overriding was proposed, which effectively guarantees the unit's safety and stability. Aiming at the changing characteristics of the steam turbine flow characteristics and the boiler's response to temperature and pressure characteristics in the state of bypass heating, an optimization strategy for coordination correction was proposed, which improved the quality of network-related control of the unit. The control scheme proposed in this paper has been applied in the supercritical once-through furnace unit. It has been verified the control strategy can realize the automatic control of the bypass system, and the control effect of the coordinated variable load is good. After the bypass RB acts, the unit can transition smoothly, realizing the bypass supply Automatic and safe control of the unit under thermal conditions.
In order to improve the flexibility of thermal power units, enhance the peak shaving capability of thermal power units coupled with molten salt heat storage system, and reduce project investment, a variety of electric heating molten salt energy storage systems coupled with thermal power plant were proposed. The thermal performance, peak shaving capacity and molten salt consumption of a 350 MW unit were analyzed with EBSILON software. An optimal system for deep peak shaving was proposed. The results show that, during the heat charging process, the electric heating system demonstrates a higher cycling efficiency as 33.2%, which enables the lowest power generation load to be reduced to below 25%. The flow rate of molten salt in this system is only 6.6%~31.2% to that of a steam heating system. During the heat discharging process, the water is drawn from the inlets of No.1 and No.2 high pressure heater. The water temperature is 182.4~242.7 ℃. The molten salt-condensed water heat exchanger is self-anti-condensation. The cycling efficiency during the heat discharging process is 32.7%~33.9% at different unit loads, indicating unit load has little effect on the cycling efficiency of the peaking shaving system. The research results can guide the engineering application of the deep peak shaving technology of thermal power units coupled with molten salt heat storage.
With the continuous progress of the work of "carbon neutrality and carbon peak", the installed scale of photovoltaic, wind power and other new energy is expanding, energy saving and consumption reduction as well as flexibility improvement become the two key tasks the thermal power units faced. Through mathematical modeling and hourly calculation analysis for the hybrid system, performance and economic characters for solar-thermal systems replacing high pressure heaters are obtained. The calculation results indicate that, using solar thermal and coal fired hybrid system can realize sharp decline of the unit coal consumption, which is a most direct and effective method for coal saving and reducing consumption, it has great significance for life prolonging of the units to be retired from active service because of high coal consumption indexes. However, the economic benefit of the system itself is insufficient. So it can be supplemented with molten salt electric heater to improve the system's frequency modulation ability and enhance the project's profitability. According to the calculation, when the frequency modulation income is not considered, the system's yield is only 6.0%, but it can be increased to 8.0% after considering the frequency modulation income. Therefore, the hybrid system has double effects in improvement of both coal saving transformation and flexibility transformation.
Tibet is located in the hinterland of the Qinghai-Tibet Plateau, the area above 4 000 m accounts for 85% of the total area of the region, its geothermal resources are very rich. To realize the reasonable exploitation of geothermal resources, combined with the carbon peaking and carbon neutrality strategy, the current situation of the development and utilization of geothermal resources in Tibet is comprehensively combed, and the suggestions for the future development of the geothermal industry are put forward. The analysis shows that the geothermal resources of hydrothermal and dry hot rock in Tibet have large storage capacity, good quality, and excellent power generation potential. The shallow geothermal resources are mainly distributed in Lhasa, which can be combined with heat pump technology for local heating. At present, there are still some problems in geological exploration, technical improvement, equipment development, and operation management. It is necessary to develop ORC units, build EGS experimental platform, and scientifically develop deep geothermal energy. The research shows that the development and utilization of geothermal resources in Tibet should follow the principles of "survey-based, power generation-based, heating-assisted, equipment upgrading, and cascade utilization", promote the scientific exploitation and efficient utilization of geothermal resources, improve the geothermal industry chain, and effectively improve the energy consumption structure in Tibet.
With the completion of ultra-low emission transformation of thermal power plants, problems such as increased costs and excessive ammonia injection have arisen. Modeling and optimization of power plant operation data through machine learning has become an important means to solve the above problems. This article reviews the commonly used machine learning algorithms and their application scenarios in reducing nitrogen oxides. In terms of algorithm, the main algorithms of data preprocessing, modeling prediction and parameter optimization and their applicability to nitrogen oxides removal are summarized. The research directions of multi-operating condition data preprocessing method and the construction method of the objective function in multi-objective optimization are proposed. For the application level of the machine learning methods, such as low nitrogen combustion in the furnace, optimization of SCR denitration system, and comprehensive energy saving and consumption reduction of the whole system, the implementation methods and corresponding effects are summarized. The future research directions of long-period dynamic modeling control and multi-power plant joint modeling have prospected.
In order to build a new power system with new energy as the main body, thermal power unit should undertake the new task of flexible operation and deep peak-regulating while maintaining power and heating supply. However, the conventional detection and communication technology is limited by the problems of poor real-time performance, slow transmission and high investment, which is difficult to support the new demand of thermal power units. Advanced detection technology and communication technology represented by 5G provide solid technical support for the state research, judgment and operation adjustment of thermal power units represented by boiler system by building a complete perceptual transmission chain, but they also face problems such as high construction investment, lack of professionals and standards. Only by setting out from the actual production, perfecting the mechanism and changing the concept, can the application effect of advanced detection and communication technology be realized. As an important part of smart power plant, the advanced detection and 5G technology will provide a solid foundation for improving the overall intelligent level of thermal power generation.