It is crucial to improve the dynamic performance of the yaw system of wind turbines in multiple operating scenarios. Therefore, a predictive control strategy for wind turbine yaw system model based on reinforcement learning is proposed, which achieves multi-objective parameter dynamic optimization through the dual-delay depth deterministic policy gradient (TD3) algorithm. Firstly, a multi-step model predictive controller for the yaw system (YMPC) is established to address the conflicting control objectives of power loss rate and yaw actuator utilization rate. Secondly, based on the optimization objectives and wind conditions of the yaw system, a dual-delay depth deterministic strategy gradient (TD3) intelligent agent is designed to determine the input state, action, and reward mechanism of the YMPC. The TD3 intelligent agent is then used to tune the weight coefficients and control step size of the YMPC. Finally, the effectiveness of this method was validated using typical daily data from wind farms in northern China. The results indicate that the proposed strategy significantly improves the overall performance of the yaw system compared with the YMPC with fixed control parameters.

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.

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.

Low-temperature adsorption technology for coal-fired flue gas pollutants can synergistically remove various pollutants and achieve near-zero emission. Focusing on the key equipment of this technology, flue gas spray cooling tower, ANSYS Fluent software is used to simulate the inside of the tower, and the impacts of various parameters are analyzed. The results indicate that, increasing the spray height effectively extends the contact time between flue gas and cooling water, thus significantly enhances heat exchange. Reducing the temperature of the cooling water strengthens the tower’s cooling capacity. Additionally, moderately reducing the inlet flue gas velocity increases its residence time in the tower, promoting more thorough heat exchange. Reducing the droplet diameter of the cooling water enhances the heat transfer efficiency by increasing the contact area. Enlarging the spray angle extends the residence time of cooling water within the tower and lengthens the contact duration with flue gas, boosting heat exchange. Increasing the cooling water flow rate expands the heat exchange area, further improving the heat transfer performance. The addition of packing material improves the heat exchange capacity of the tower while conserving cooling water. Comprehensively optimizing these parameters can substantially reduce the temperature of cooled flue gas, providing theoretical support for the design, manufacturing, and optimization of spray cooling towers in the low-temperature adsorption technology for coal-fired flue gas pollutants.

To solve the problems of slagging and burner burnout caused by lean coal boilers which convert to firing Shenhua bituminous coal, a 600 MW supercritical opposed firing boiler was taken as the research object. Through thermal calculation and numerical simulation analysis, a feasibility study for the combustion system retrofit scheme was carried out with emphasis. The results show that, by adopting differentiated heat load design, inclined installation of side wall burners into the furnace, and multiple dimensions of wall mounted wind, the heat load in the burner area reduced from 1.71 MW/m² to 1.44 MW/m², and the flue gas temperature at the furnace outlet decreased from 1 058 ℃ to 1 010 ℃. The performance test results after the retrofit show that at rated load, the unburnt carbon content of coal ash decreased from 6.06% to 1.42%, the boiler efficiency increased from 92.76% to 94.03%, and the NOx emissions at the furnace outlet reduced by 50%~60% at various loads. The boiler can operate safely and efficiently for a long period. The proposed transformation technology scheme has guiding significance for the optimization and retrofit of combustion systems of similar units under the condition of converting low volatile coal to bituminous coal.

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%.

For a supercritical carbon dioxide (S-CO₂) recompression Brayton (RB) system with two-stage compression and intercooling process, two system models with different layouts are constructed. The effects of key parameters such as low-pressure stage pressure ratio and split ratio on the system performance are explored. The results indicate that, the minimum and optimum splitting ratios exist for the RB cycle, the two-stage compression cycle of the main compressor (TCIP-RB), and the two-stage compression cycle of the recompressor (RTCIP-RB) under the design conditions. Moreover, the thermal efficiency of the TCIP-RB cycle is higher than that of the other two cycles within a certain range of split ratios. When the above three systems adopt the optimal split ratios, the maximum efficiency of the TCIP-RB cycle is 50.95%, which surpasses that of the RB and RTCIP-RB cycle by 3.20% and 3.98%, respectively. At different low-pressure stage pressure ratios, TCIP-RB and RTCIP-RB cycles have an optimal split ratio to maximize the thermal efficiency of the system, and the maximum thermal efficiency decreases with the increase of the low-pressure stage pressure ratio.

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⁺.

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.

The formation and emission of SO₃ in coal-fired flue gas pose serious threats to both the safe and economical operation of power plants and the atmospheric environment. To solve this problem, the SO₃ removal performance of sodium-based, calcium-based and magnesium-based absorbents is investigated, and the performance variations of Na₂CO₃, Ca(OH)₂ and CaO under different operating conditions are studied. The results indicate that, under the coexistence of SO₂ and SO₃, the absorbers would react with SO₃ in the flue gas preferentially, and the effectiveness of SO₃ removal by various absorbents ranked from highest to lowest is as follows: Na₂CO₃>NaHCO₃>Mg(OH)₂>MgO>Ca(OH)₂>CaO. Under certain experimental conditions, the SO₃ removal efficiencies of all the absorbents could reach higher than 80% when the chemical equivalent ratio of absorbent to SO₂ reached 2:1. Pre-calcination treatment for the absorbents enhanced their pore structures, facilitating SO₃ diffusion into the absorbent and improving the SO₃ absorption efficiency. Increasing reaction temperature, chemical equivalent ratio, and initial SO₃ mass concentration can promote the SO₃ removal. Additionally, a moderate increase in H₂O volume fraction aided SO₃ removal. When the absorbent is significantly excessive, external diffusion is the main controlling step affecting the chemical reaction rate, while the type of absorbent has a relatively minor impact on it.