According to GB/T10184—2015, the calculation model of blast furnace gas boiler efficiency is constructed, and the calculation method of blast furnace gas boiler efficiency is analyzed. The results show that the calculation methods of gas moisture content and low-level calorific value are different due to the difference of gas benchmarks.Three methods for solving the excess air coefficient, actual flue gas volume and CO₂ content in the flue gas are proposed for blast furnace gas boilers, and a correction method for exhaust gas temperature of blast furnace gas boilers with gas heaters is proposed;The calculation of some formulas in the GB/T10184—2015 needs to be further discussed, and appropriate modifications can be made.

Geothermal power generation, as one of the main ways to develop and utilize geothermal resources, is of great significance to promote the low-carbon and clean energy structure and the realization of the “dual carbon”. Firstly, the development history of geothermal resources in the world is analyzed. Then, main geothermal power generation technologies such as dry steam power generation, flash steam power generation, binary cycle power generation and wellhead power generation technology are overviewed. On this basis, the hot dry rock power generation, thermovoltaic power generation, supercritical CO₂ cycle power generation, combined power generation technology and multi-energy eomplementary power generation technologies such as geothermal-solar, geothermal-wind, geothermal-biomass, and geothermal-ocean energy, are elaborated in detail. Finally, combining with the current situation and existing problems of geothermal power generation in China, some suggestions for the development of geothermal power generation are put forward, to provide reference for the future development of geothermal power generation.

To address the demand for low-carbon transition in coal-fired power plants, ammonia, as a zero-carbon fuel and efficient hydrogen storage carrier, provides a novel pathway for carbon reduction in the thermal power industry. The key technologies and research advances in green ammonia synthesis, storage, transportation, and ammonia-coal co-firing are systematically reviewed from the perspective of the “production-storage-transportation-utilization” whole industry chain, and the economic feasibility is also evaluated. The study reveals that, the second-generation low-temperature and low-pressure synthesis technology (Fe/Ru catalysts) exhibits the greatest industrial potential for green ammonia production, but requires breakthroughs in enhancing catalytic activity and dynamic matching technologies for renewable energy-based hydrogen-ammonia synthesis systems. It is urgent to develop 100 000-ton-level cryogenic storage tanks and long-distance liquid ammonia pipelines, and establish a “West-to-East Ammonia Transmission” network to support large-scale applications. Ammonia-coal co-firing can achieve NO_x emissions comparable to pure coal combustion by optimizing ammonia injection positions (post-injection in low-oxygen zones), air staging (equivalence ratio of 1.1~1.3 in primary zone), and ammonia blending ratios, alongside designing low-NO_x co-firing burners. However, the weakened radiative heat transfer and enhanced convective heat transfer post-co-firing necessitate compatibility adjustments in boiler steam-water systems. When the cost of renewable electricity decreases to 0.10 yuan/(kW·h) with carbon price exceeding 370 yuan/t, or by utilizing curtailed wind/solar power (with near-zero electricity costs), green ammonia is more competitive than coal. In the future, it is necessary to promote the implementation of technology through green ammonia cost reduction, carbon price mechanism and policy support. This study provides comprehensive technical references and economic optimization strategies for scaling up green ammonia co-firing in coal-fired power plants.

Carnot battery (CB) is an energy storage technology with the advantages of high energy storage density and low investment cost. The single-stage heat pump of basic Carnot battery have a low coefficient of performance (COP) under high energy storage density conditions, resulting in a phenomenon of high quality but low utilization of heat. In order to solve this problem, a CB using cascaded heat pump (CHP) and supercritical organic Rankine cycle (ORC) is proposed. Through modeling and analysis, the optimal combination of CHP-CB working fluids is obtained, and the effects of waste heat source temperature, high and low temperature heat storage tank temperature, CHP intermediate temperature on system COP, energy conversion efficiency, energy storage density (E_D) and system exergy loss are discussed. The results show that under high energy density conditions, the COP of the CHP-CB is about 23.5% and 26.9% higher than that of the basic CB when the temperature of the low-temperature storage tank is 50 ℃ and 32 ℃, respeetively. When the temperature of the low-temperature storage tank is 30 ℃, the energy conversion efficiency of the CHP-CB can reach 63.11%. The E_D can reach 13.9 kW·h/m³ when the temperature difference between the high- and low-temperature storage tank is 93 ℃, and cascade heating for the heat storage working fluid can be realized.

The anti-freezing operation parameters of indirect air-cooled finned bundle are insufficient at present. To solve this problem, this research firstly concludes the anti-freezing model of finned tube bundle, including the thermal equilibration equations, water side and air side transport equations, as well as anti-freezing constrains. Secondly, based on the co-current and counter-current air-cooled finned tube bundles, the critical anti-freezing characteristics and margin are analyzed. Then, the critical values are discovered for finned tube bundles with middle inlet, left inlet and side inlet patterns. The research shows that, as the ambient temperature or inlet water temperature reduces, as well as the ambient wind increases, the critical anti-freezing water flow rate ascends. Besides, when the inlet water temperature decreases, the wind effects get intensified. The anti-freezing performance of counter-current finned tube bundle is inferior to that of the co-current type, meanwhile the difference becomes expanded if the wind increases or water inlet temperature decreases. The effects of inlet water temperature elevation on anti-freezing margin can be classified into three levels, which are termed as obvious range (0 ℃, 10 ℃], slow range (10 ℃, 20 ℃], and stable range (20 ℃, 40 ℃]. Therefore, power plants should not always increase the water flow rate for anti-freezing operation. The air-cooled finned tube bundle with middle inlet pattern has better anti-freezing performance than others, so it’s suggested preferentially for coal-fired or nuclear power plants. This research may provide guidelines of anti-freezing operation for dry-cooling power stations in China.

When multiple units are used for combined heating, the distribution of thermoelectric loads among the units significantly affects overall energy consumption. For a thermal power plant where Unit 1 and Unit 3 adopt a dual-mode coupled heat-supply method with zero output of the low-pressure cylinder and steam extraction, and Unit 2 and Unit 4 adopt a triple-mode coupled heat-supply method with high back-pressure, heat pump, and steam extraction, an off-design condition model was established using EBSILON software. The thermoelectric characteristics and energy consumption characteristics were analyzed by adjusting parameters such as main steam flow, zero output steam volume of the low-pressure cylinder, heat supply power of the heat pump, and high-back-pressure heat-supply flow rate. The operational boundaries of electrical and thermal loads and the relationship between coal consumption and thermoelectric load were fitted using the least squares method. Under the fixed boundary conditions for the entire plant’s heating load and power supply load, the optimization of thermoelectric load distribution was achieved using particle swarm optimization. The results indicate that large-capacity high back pressure heat pump units should provide heat load, and small-capacity high back pressure heat pump units should provide electric load. After optimization, the total coal consumption of the whole plant was reduced by 0.6~10.0 t/h, resulting in a degree of optimization of 0.3%~3.9%.

Phosphate ester fire-resistant fluids, serving as hydraulic working medium for the speed regulation system of steam turbines, play a crucial role in the normal operation of steam turbines. Currently, imported products dominate the phosphate ester fire-resistant fluids market for the speed regulation system of steam turbines in domestic power generation units. To break the power industry’s high dependence on imported fire-resistant fluids, it is imperative to develop domestic phosphate ester fire-resistant fluids through independent research and application. Through performance evaluation of various domestic tri-aryl phosphate esters, tri-(dimethylphenyl) phosphate was identified as the optimal choice for domestic fire-resistant fluid development. Via oxidation and adsorption refining processes, the stability of the domestic tri-(dimethylphenyl) phosphate was significantly enhanced, resulting in the successful development of high-performance phosphate ester fire-resistant base oil. After the research on various additives, an optimized additive formulation was established, ultimately producing high-performance phosphate ester fire-resistant fluid that meets the new fluid requirements specified in Guide for Operation and Maintenance of Phosphate Ester Fire-resistant Fluid Used in Power Plant (DL/T 571—2014). Static and dynamic simulated aging tests demonstrated that the domestic phosphate ester fire-resistant fluid exhibits superior anti-aging performance compared to the commercially available alternatives. Following one year of industrial demonstration in power generation units, the fluid maintained new-oil quality standards throughout the application period, with the turbine governing system operating normally.

In response to current issues faced by coal-fired power plants, such as high fuel costs, weakly stable combustion performance at low loads, and insufficient peak-shaving capabilities, an integrated operational scheme is proposed based on the natural endowments of renewable energy surrounding the power plant, which utilizes photovoltaic power generation distributed in plants to produce hydrogen and oxygen via electrolysis of water, then to achieve hydrogen and oxygen co-firing in coal-fired boilers. By constructing a full-size numerical model for a tangentially coal-fired boiler, the calculation accuracy of temperature field, species concentration, and carbon content in fly ash is verified under pure pulverized coal combustion conditions, which could provide a benchmark for optimization of hydrogen and oxygen blending. Based on the typical application scenario of a 20 MW photovoltaic power generation to hydrogen and oxygen production in the plant, the effects of three mixing methods of hydrogen and oxygen on combustion efficiency, burnout characteristics and NO_x formation in the furnace are systematically studied. The results show that, a co-combustion mode which utilizes an independent hydrogen nozzle in conjunction with primary air mixing with oxygen can improve the combustion performance significantly. The carbon content in fly ash at the furnace outlet reduces to 0.97%, and the combustion efficiency is notably enhanced compared with that under pure coal combustion condition. At the same time, the reduction effect of reactive species generated by hydrogen combustion on NO_x leads to a decrease in NO_x emission mass concentration in the flue gas to 294.0 mg/m³, which is decreased by about 25% compared with that under baseline condition of pure coal combustion. This model achieves dual-benefit of coal substitution and combustion optimization through hydrogen and oxygen production from renewable energy, which not only reduces coal consumption but also expands the lower limit of stable combustion load for coal-fired boilers. It provides a technically feasible implementation reference path for the decarbonized retrofitting and flexibility improvement of coal-fired units.

The supercritical carbon dioxide (S-CO₂) cycle power generation technology has become an epoch-making and revolutionary frontier technology in the field of thermal power generation because of its own technical advantages. Due to the very harsh working environment, S-CO₂ is easy to cause corrosion problems of equipment materials. In order to ensure the safe and effective operation of S-CO₂ system, the range of working medium parameters and candidate materials of the system’s key equipment are introduced. The current research status of corrosion behavior of metal materials in S-CO₂ environment are then reviewed. The corrosion mechanism in S-CO₂ carbon environment is elaborated in detail. The influences of temperature, pressure, impurities, flow rate and material composition on S-CO₂ corrosion process are summarized. Meanwhile, the research progress of S-CO₂ corrosion prevention and control technology is introduced. Finally, the shortcomings of existing research and the main direction of future research wereare summarized, so as to provide scientific basis for the safe operation of S-CO₂ recycling system in China.

To improve the control effect of key parameters and energy conversion efficiency of ultra-supercritical coal-fired power generation units during load cycling process, 600 MW class ultra-supercritical coal-fired power generation units are taken as the research objects to carry out modeling and verification. The deviation of key thermal parameters meets the specified range of thermal power simulation standard. The spatiotemporal distribution model of internal heat storage in thermal system of coal-fired power generation units is established, and the water-fuel ratio and flue gas damper opening control logic of the feedforward internal heat storage state of the unit are proposed. The real-time heat storage state of the unit during the load cycling process is fed forward to the flow rate of feed water, coal, and flue gas damper control. The simulation results show that, when the unit load cycling rate varies from 1.0% Pe/min to 3.0%Pe/min within 40%~70% THA load range, the absolute value of the cumulative main steam temperature deviation rate decreases by 27%~31%. The average power generation standard coal consumption rate of the unit decreases by 0.37~0.65 g/(kW·h) during the transient process. The proposed control strategies improve the control accuracy of key thermal parameters and the energy conversion efficiencies of the ultra-supercritical coal-fired power generation units during load cycling transient processes.