With the increase in parameters and capacity of newly built coal-fired units, the expansion of critical long-distance and large-diameter pipelines due to high parameters becomes more significant, making the design of supports and hangers particularly important. In a case involving a 2×660 MW ultra-supercritical unit, the diagonal brace of a rigid hanger tripod supporting the main steam pipeline buckled, resulting in a pipeline subsidence of nearly 130 mm. A comprehensive inspection of the pipeline supports and hangers was conducted, along with mechanical analysis of the statically indeterminate tripod structure and stability analysis of the diagonal brace. The study concluded that the failure of the diagonal brace and the pipeline sinking were primarily caused by an incorrect design of the radial horizontal restraint gap. Additionally, the excessive constant force of the constant hanger also contributed to the damage of the diagonal brace. This research not only analyzed the design flaws of the pipeline supports and hangers, but also proposed an engineering solution to optimize the restraint gap, which was validated on-site. A rectification plan involving horizontal limit adjustment and pipeline lifting was developed and implemented, successfully restoring the pipeline to its designed state and resolving the issue. This problem is highly representative in the construction of large-scale power units and should draw the attention of designers to avoid similar issues in future projects.

With the rapid development of energy storage industry and the continuous increase in the installed capacity of energy storage power stations, safety accidents in electrochemical energy-storage power stations have become increasingly frequent, and safety issues have gradually become a key factor restricting the large-scale development of the industry. Therefore, the current policies and standards related to safety risk assessment of electrochemical energy storage power stations at home and abroad are systematically reviewed at first. Then, by analyzing typical safety incidents of electrochemical energy storage power stations, the safety risk points of such power stations are summarized. Based on this, the research progress of the theory and evaluation methods of safety risk assessment of electrochemical energy storage power stations is summarized, from the aspects of battery body, power station working environment, external stimulation and human factors. Finally, the safety development of energy storage power stations in the future is discussed from improving the safety evaluation policies and standards of energy storage power stations, enhancing the construction of the safety assessment system for energy storage power stations, improving the safety and operation management system of energy storage power stations, and strengthening the cultivation of professionals in the energy storage field. It is hoped that this will provide some references for subsequent related researches.

To achieve efficient coupling between coal-fired power plants (CFPP) and compressed air energy storage (CAES), a system that couples the flue-gas side of CFPP with CAES is proposed. During the energy release phase of this coupled system, the flue gas from CFPP is used to heat the high-pressure air before it enters the expander. This avoids introducing additional heat sources, which would increase costs, or extracting steam from the turbine side to heat the high-pressure air, which would affect the output of the thermal power unit. Subsequently, to reduce the effect of extracted flue gas on the operation of a single thermal power unit, a CAES coupled system sharing the flue gas of two thermal power units is established. Based on the above thermodynamic models of the systems, modeling is carried out using EBSILON software and performance analysis is conducted. Then, an optimal economic operation strategy for the plant-level coupled system is proposed. The results show that, at full load, compared with the steam-coupling scheme, the flue-gas-coupling scheme reduces the standard coal consumption rate by 2.15 g/(kW·h), increases the heat consumption rate by 37.06 kJ/(kW·h), raises the energy utilization coefficient by 0.33 percentage point, and decreases the auxiliary power rate by 0.20 percentage point. The overall electrical efficiency, round-trip efficiency, and CAES operating efficiency of the flue-gas-side coupling are all higher than those of the steam-side coupling. After the economic optimization of the plant-level coupled system, the net revenues of four typical days increase by 143 700, 157 600, 188 100 and 208 700 yuan, respectively.

The dynamic models of steam generation system and power generation system are developed to study the dynamic characteristics of power-to-heat molten salt heat storage and power generation system, and the reliability of the models is validated. The dynamic characteristics of the system are analyzed for the disturbance of molten salt work temperature, flowrate and steam valve opening. Moreover, the performance of the system in the load reduction transient process is investigated in the 100%THA~50%THA load interval. The results show that, the main steam temperature and reheat steam temperature respond quickly to the molten salt temperature disturbance, and their response is obviously faster than that of the unit load and main steam pressure. The molten salt flowrate disturbance has a significant effect on the unit load and main steam pressure, and the unit load increases by 12.44% and the main steam pressure increases by 1.18 MPa with 15% increase in molten salt flowrate. The main steam valve opening controls the main steam pressure and load fluctuation. With the addition of the control system, the maximum load reduction rate of the unit in the 100%THA~50%THA load interval is 14%Pe/min with the limiting condition of temperature deviation.

In order to effectively improve the energy efficiency and operational flexibility of solar power generation, an integrated system coupling solar photovoltaic, solar thermal and compressed air energy storage is proposed. During the day, the compressed air energy storage system will store the photovoltaic abandoned power, and transfer the compression heat to the photothermal power station. At night, the compressed air energy storage system releases air and uses water supply of the photothermal power station to heat up, thereby increasing the power generation load of the unit. Based on the system simulation, the coupling scheme is analyzed thermodynamically and economically. The overall generation efficiency of the coupled system is 41.24%, while the overall exergy efficiency is 66.79%. The round-trip efficiency of the compressed air energy storage system is 72.14%, while the exergy efficiency of the compressed air system is 84.30%, both of which have increased significantly. The peaking depth of the coupled system is 7.02% in the daytime and 19.69% in the evening. In addition, the dynamic recovery cycle of the coupling scheme is 3.10 years, and the net present value is 41.350 6 million yuan.

As an emerging large-scale electricity storage technology, the Carnot battery has the advantages of low cost, large capacity, and being free from geographical limitations. Aiming at the current situation that the low discharge cycle efficiency restrains further improvement of round-trip efficiency of the Carnot battery, combined with the heat demand of the thermally integrated Carnot battery and the relatively high discharge efficiency of the Kalina cycle, a heat pumped-Kalina cycle Carnot battery system driven by extraction steam of a coal-fired power station is proposed. A thermodynamic model of the Carnot battery system is established, and the influences of thermal energy storage temperature, temperature difference in thermal energy storage, and ammonia mass fraction on thermodynamic performance of the Carnot battery are mainly studied. The results show that, with different temperature differences of thermal energy storage and at different temperatures, the round-trip efficiency can reach 44.8%~108.0%. With the increase of the ammonia mass fraction, the round-trip efficiency will be significantly improved. However, when the ammonia mass fraction exceeds 90%, the efficiency will drop sharply, and the Kalina cycle is close to a one-component cycle. Therefore, when designing a Carnot battery based on the Kalina cycle, the ammonia mass fraction should be controlled within 80%~90%.

Improving the flexibility of coal-fired power units is the key to achieving a green and low-carbon power system. Molten salt energy storage technology, as a sensible heat energy storage technology, can provide frequency regulation, peak regulation, and industrial heating decoupling support for power generation units. Combining with the engineering application of a coal-fired power unit coupled with molten salt energy storage, the thermal performance of heat storage, heat release and energy cycling are systematically analyzed, and performance evaluation indicators are proposed. The results show that, the molten salt thermal storage system significantly enhances the flexible operation capability of the unit, achieves decoupling between industrial steam supply and deep commissioning peak of the unit, and improves the frequency regulation performance by 150%. The thermal efficiency of the thermal storage system is maintained at around 92%. This study provides a reference for the application of flexibility renovation projects for coal-fired power plants based on molten salt thermal storage technology.

Constructing a large-scale virtual power plant (L-VPP) based on coal-fired units is a vital strategy for achieving “dual-carbon” goals by enabling renewable energy integration and supporting the transition of coal-fired power generation. A dynamic simulation model of the L-VPP and a source-storage frequency regulation control system model are established, which include a 350 MW coal-fired unit, a 100 MW photovoltaic unit, a 90 MW·h battery energy storage system, and internal loads. The frequency response characteristics of the L-VPP are analyzed for various control systems and at different load ramp rates of the coal-fired unit. The results reveal that, the load ramp rate of the coal-fired unit is a critical constraint on frequency response capability when storage capacity is limited. The complementary frequency response characteristics between the source and storage are obtained, leading to a coordinated control strategy that incorporates auxiliary power commands and cyclic determination mechanisms. Simulations demonstrate that the proposed strategy lowers the frequency nadir by 0.06 Hz and shortens the steady-state recovery time by 18.6%. Furthermore, to achieve a steady-state error within the frequency dead band, the load ramp rate of the coal-fired unit is increased from below 3.50 MW/min to 7.00 MW/min. This strategy offers technical guidance for the safe and efficient operation of large-scale virtual power plants.

Co-firing biomass in coal-fired plants is considered as one of the important technologies for achieving carbon emission reduction. Based on the 660MW ultra-supercritical lignite coal fired plant in Inner Mongolia, this study conducted the first domestic experiment on co-firing cow manure. Cow manure is a typical herbaceous biomass. the first domestic large scale coal-cow manure co-combustion experiment in a 660 MW ultra supercritical lignite-fired power unit in Inner Mongolia was carried out. The ability of coal mill to grind biomass and coal mixed fuels was investigated, and the effect of mixing compacted cow manure on the milling performance was analyzed. Moreover, the effects of co-firing compacted cow manure on the combustion characteristics, unburned carbon content in fly ash, boiler efficiency, and pollutant emissions at different loads were studied. The results indicate that, without the addition of new devices, the change in coal mill current before and after co-firing 15% and 20% compacted cow manure with single coal mill changed slightly. With co-firing 15% compacted cow manure and the coal fineness R₂₀₀ increasing from 8.3% to 12.4%, the R₉₀ increased from 35.8% to 40.0%. With co-firing 20% compacted cow manure and the coal fineness R₂₀₀ increasing from 8.3% to 14.4%, the R₉₀ increased from 35.8% to 54.4%. The pressure difference between the coal mill inlet and outlet varied significantly and was closely related to the coal feed rate. With the furnace compacted cow manure co-firing ratio of 2.9% (15% co-firing with coal mill B) and 6.4% (20% co-firing with coal mill B), the changes of exhaust temperature before and after co-firing were both between 1.0~2.5 ℃. With the furnace compacted cow manure co-firing ratio of 7.1% (16.0% co-firing with coal mills B and D) and 8.7% (15% co-firing with coal mills B, C, and D), the exhaust temperature before and after co-firing increased by 3.3 ℃ and 3.6 ℃ at 450 MW and 550 MW, respectively, which was significant. At 250 MW, 450 MW, and 550 MW loads, the change of CO mass concentration was less than 5 mg/m³, and the decrease in boiler thermal efficiency before and after co-firing remained 0.06~0.28 percentage points. Co-firing compacted cow manure can reduce NO_x and SO₂ emissions. When the mixing ratio of compacted cow manure on two and three coal mills was 15% and 20%, the annual CO₂ emission reduction would be 140 312, 210 467, 160 356 and 240 534 tons, respectively.

A comparative test was conducted on operating oil samples from wind turbine gear oil and a fresh oil sample, revealing that the Fe³⁺ content was the most rapidly deteriorating indicator. The SG-PEI adsorbent was prepared by loading polyethyleneimine (PEI) onto a silica gel material (SG) through impregnation modification, and its characteristics were evaluated. The adsorption isotherms and kinetics of Fe³⁺ on SG-PEI were thoroughly investigated. The results indicated that, the adsorption isotherm of Fe³⁺ on SG-PEI conforms to Langmuir model. The saturated adsorption capacity of SG-PEI for Fe³⁺ was 28.71 mg/g, representing a 39.2% improvement compared to SG (20.63 mg/g). The adsorption process of Fe³⁺ on SG-PEI adhered to the pseudo-second-order kinetic model, with adsorption process occurring as a spontaneous exothermic reaction. Under optimal conditions of an adsorption temperature of 60 ℃, an adsorption time of 120 min, and an oil-adsorbent ratio of 100:3, the removal rate of Fe³⁺ from wind turbine gear oil by SG-PEI reached 96.23%, which is 29.43 times higher than that of the 801 adsorbent (3.27%) and 185.06 times higher than that of Al₂O₃ (0.52%). The SG-PEI has a good prospect for applications due to its high adsorption capacity and selectivity for Fe³⁺.