To explore the ignition and stable combustion performance of ammonia fuel in simulated combustion chambers of gas turbines, ignition and combustion experiments were conducted on ammonia gas with different preheating temperatures and cracking degrees, and the ignition and combustion laws of ammonia fuel under certain experimental conditions were obtained. The results indicate that, stable combustion of ammonia requires a cracking degree of not less than 30% and an air preheater temperature of not less than 643 K. Within the temperature range of 743~943 K and combustion duration of 5~40 seconds in the air preheater, the internal temperature, tail temperature, and pressure of the combustion chamber generally increase with the preheater temperature and combustion duration. The NO emission volume fraction is significantly affected by the temperature of the preheater, it reaches the minimum (376 μL/L) at 673 K when the combustion efficiency is 96%. The zero dimensional simulation results show that, increasing pressure, ammonia cracking degree and temperature can help shorten the ignition delay time, and higher hydrogen content and slightly enriched combustion state can promote the increase of laminar flame velocity and optimize the combustion of ammonia.

Induced draft fans in power plants run under complex and harsh conditions, where various faults often occur. These faults not only affect the fans’ safety and stability but also pose an indirect threat to normal operation of the boiler system. Thus, early fault monitoring and prompt, accurate diagnosis are essential to ensure the power plants’ operation efficiency and safety. Common fault types of forced draft fans and their potential effects are analyzed and summarized. Three typical fault types and their causes are explained in detail. Fault monitoring and diagnosis methods are elaborated from both quantitative and qualitative perspectives, including measurement point installation and data processing techniques. Each method’s advantages and disadvantages are analyzed, and suitable applications for different fault types are discussed, along with proposed targeted improvement measures. Finally, key challenges of fault diagnosis are identified, and future development directions for forced draft fans’ fault monitoring and diagnosis are outlined.

Supercritical carbon dioxide (S-CO₂) in horizontal tube with circumferential heating and semicircle heating is investigated numerically based on pseudo-boiling theory. The phase distribution of supercritical fluid in the tube is obtained. It is found that the heat transfer performance of supercritical fluid is determined by the thickness of vapor-like film on tube, which can be characterized by supercritical K number, involving the balance between evaporation momentum force and inertia force. The increasing thickness of local vapor-like film can trigger heat transfer deterioration. There are both overshoot wall temperature along the flow direction and non-uniform wall temperature in the circumferential direction. The emerging condition of heat transfer deterioration can be accurately predicted by supercritical boiling number SBO. Under working conditions where the pressure p is 8~20 MPa, and the range of mass flux G and heat flux density q_w is 300~1 300 kg/(m²·s) and 42~500 kW/m² respectively, compared with the circumferential heating tube, the semicircle heating tube behaves thinner vapor-like film to enhance the heat transfer performance. The critical SBO to heat transfer deterioration rises from 6.179×10^–4 to 9.798×10^–4. Furthermore, the semicircle heating tube keeps more uniform vapor-like film, the maximum temperature difference between the top and bottom generatrix of tube wall changes from 116.3 K to 57.1 K. Due to the ability to repress heat transfer deterioration and non-uniform wall temperature, semicircle heating is recommended to ensure the safe operation of horizontal heat exchangers in advanced supercritical CO₂ system.

The current coal-fired unit coupled with molten salt heat storage system technology has the problems of limited peak shifting capacity and poor peak heat economy. To address these issues, a new system of coal-fired unit coupled with compressed steam and molten salt heat storage is proposed, specifically including single molten salt heat storage scheme and double-molten-salt-heat-storage scheme. The system performs multi-stage compression of extracted steam through a multi-stage compressor and uses molten salt for heat storage. The compressed steam is eventually condensed to water so that its latent heat of condensation will be utilized. The simulation model of the coupled system scheme is established by EBSILON software. The research results indicate that, compared with the conventional molten salt heat storage technology scheme, the compressed steam and molten salt heat storage system can effectively reduce the effect of steam extraction and heat storage on the thermal economy of the system, and expand the peaking range of the unit. Specifically, the round-trip efficiencies of the single molten salt and double-molten-salt scheme are improved from 27.43%~38.03% to 62.13%~64.56% and 65.69%~66.93%, respectively, and the minimum outputs are reduced from 20.91%Pe to 19.84%Pe and 19.28%Pe, respectively, compared with the conventional scheme. Considering the thermodynamic and economic performance of the system, the single molten salt scheme is the best choice.

The coordinated operation of coal-fired power plant (CFPP) with large-scale energy storage systems can effectively regulate the flexibility of power system and smooth the renewable power output. A gas-liquid interconversion carbon dioxide energy storage system coupled with a CFPP was proposed, which recovers compression heat using condensate and feedwater of CFPP and preheats turbine inlet CO2 through drain water, realizing thermal decoupling of charge and discharge processes without heat storage devices. Based on the mathematical models of the coupling system, the system coupling schemes were designed and optimized, and a comparative performance analysis with stand-alone system was conducted. The results show that, the compression heat cascade recovery boosts the exergy efficiency of last-stage intercooler from 73.3% to 89.6%, and the exergy efficiency of the first-stage preheater improves from 53.1% to 89.7% by replacing extraction preheating with drain water cascade preheating. In the optimal coupling scheme, the system energy storage efficiency improves from 63.6% to 76.8% compared to the stand-alone system, and the levelized cost of electricity reduces from 0.130 dollar/(kW·h) to 0.093 dollar/(kW·h), with a slight reduction in round-trip efficiency to 63.2%. The turbomachinery and heat exchangers, representing the main contributors to the total system exergy destruction and investment cost, are key components in improving thermodynamic and economic performance. Increasing the discharge power to 90 MW reduces the levelized cost of electricity to 0.089 dollar/(kW·h) and expands the peak regulating range to 86.4%~107.6%.

Thermal power units, as a cornerstone of conventional electricity generation, release considerable quantities of waste heat during their operation. If not effectively harnessed, this waste heat will result in substantial energy inefficiency and exacerbate environmental challenges. Consequently, the efficient recovery and utilization of waste heat from thermal power units represents a pivotal strategy for optimizing energy use and mitigating carbon emissions. The energy-saving and carbon-reduction potential of various cycle components in thermal power units should be thoroughly explored. Conducting parameter matching to enable the efficient and comprehensive utilization of waste heat at different grades in thermal power units holds significant importance for achieving deep energy conservation and emission reductions in China’s thermal power industry. A comprehensive examination of waste heat recovery in thermal power units is provided. It begins by identifying the primary sources and distinctive characteristics of waste heat. Subsequently, it delves into specific recovery methodologies and their technical principles, encompassing low-pressure turbine exhaust heat utilization, flue gas heat recovery, boiler blowdown and continuous blowdown heat recovery. For each method, the system configuration, current deployment status, economic feasibility, and environmental benefits are analyzed in detail. The strengths and limitations of these approaches are critically evaluated. Finally, the future prospects and developmental trajectories of waste heat recovery technologies in the thermal power sector are thoroughly explored and anticipated.

Thermochemical thermal storage has attracted wide attentions because it has high thermal density heat storage and can realize seasonal thermal storage and long-distance transportation. The CaCO₃/CaO reaction system, as one of the most promising thermochemical heat storage materials, has problems such as particle aggregation and sintering as the number of heat storage cycles increases, and the material gradually loses its activity. To solve this problem, composite CaO materials doped with Al₂O₃ or CeO₂ were synthesized by the template method. The microstructure of the materials and the effect of chemical doping on the cyclic stability of the composite CaO materials were investigated by means of characterization tests such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and synchronous thermal analyzer (STA). The effect of chemical doping on exothermic reaction temperature range of the composite CaO materials was analyzed. The results show that, the CaO prepared by the template method has a richer pore structure and a superior cycling stability than the CaO obtained by decomposition of CaCO₃. When the doping molar ratio of CaO to Al₂O₃ is 100.0:2.5 (Ca:Al), the composite has the best cycling stability. After 30 cycles, the effective conversion rate decays by only about 7.1% from 0.70 to 0.65 and the exothermic energy density is 2 057 kJ/kg. The cyclic stability of the composite is better than that of CaO when the molar ratio of CaO to CeO₂ doping is 100.0:10.0 (Ca:Ce=100.0:10.0). It is found that doping with Al₂O₃ decreases the onset temperature of the exothermic reaction of the CaCO₃/CaO reaction system, whereas CeO₂ increases the onset temperature.

The sterilization effect of chlorine-containing disinfectants does not hinge on the total available chlorine concentration, but rather on the concentration of hypochlorous acid (HClO) molecules. To reduce the cost of circulating water sterilization in thermal power plants, HClO solution was used to sterilize circulating water. The HClO solution was prepared from sodium hypochlorite (NaClO) solution, CO₂ and pure water by non-electrolytic method, and experimental study on application performance (including stability and sterilization effect) of the HClO solution was conducted. The results showed that, the mass concentration of HClO in NaClO solution was extremely low, the mass fraction of HClO to available chlorine was only 0.690%~0.012% in NaClO solution with mass concentration of available chlorine in the range of 100~2 000 mg/L, which could be increased to 94.91% by reacting with CO₂, thereby improving the sterilization efficiency. When 30, 60, 80, and 90 mg/L stabilizer were added, the decomposition rate of HClO solution with mass concentrations of 500, 1 000, 1 500 and 2 000 mg/L could meet the requirements for a shelf life of one year of the Disinfection Technical Specification. When the dosage of NaClO and HClO (calculated by available chlorine) was 5 mg/L and 0.06 mg/L，the sterilizing time was 120 min and 15 min, the sterilizing rate could reach 90%, and it can be seen that HClO was more economical and efficient for sterilization. HClO solution can reduce the cost of circulating water bactericides in thermal power plants by more than 55% compared with that of conventional NaClO.

Researches on the application of calcium carbide residues in carbon fixation is mainly conducted at a macroscopic level, with limited studies exploring the carbon fixation mechanism of calcium carbide residues from a microscopic perspective. It remains unclear whether the various impurities present in calcium carbide residues adversely affect the CO2 adsorption activity of this material. To solve this problem, the phase compositions of calcium carbide residues before and after calcination were analyzed using X-ray diffraction, and density functional theory was employed to construct the most stable low-index crystal planes such as CaO-CaO (0 0 1), CaO-Fe₂O₃ (0 0 1), CaO-Al₂O₃ (1 1 1), CaO-MgO (1 0 0) and CaO-SiO₂ (0 0 1). Moreover, the adsorption properties of CaO clusters on various impurity-supported surfaces and doped surfaces were simulated, along with the capabilities of these surfaces to support the adsorption of CO₂ molecules. The adsorption energy, charge transfer, density of states, and differential charge density of each adsorption system were analyzed. The results indicate that SiO₂ does not significantly influence the adsorption process. The four different supported surfaces enhance the anti-sintering performance of calcium carbide residues, with the strength of the effects ranked as follows: Al₂O₃ > Fe₂O₃ > MgO > CaO. The adsorption energy on the Al₂O₃ supported surface is –8.82 eV, which is 1.24, 2.45, and 3.69 times greater than that on the Fe₂O₃, MgO, and CaO supported surfaces, respectively. The capacities of the various surfaces to support CaO in the adsorption of CO₂ are similar, with the electron transfer quantities for the CaO clusters adsorbing CO₂ on the CaO, Fe₂O₃, Al₂O₃, and MgO supported surfaces being 0.67, 0.68, 0.71 and 0.66 e, respectively. The presence of impurities can effectively improve the anti-sintering performance of calcium carbide residue as a CaO-based material, but can not significantly enhance the CO₂ adsorption effect. Compared with the pure CaO supported surfaces, the doped surfaces exhibit a stronger capability for CaO to adsorb CO₂, with adsorption energy and electron transfer quantities being –4.92 eV and 0.71 e, respectively.

Proton exchange membrane (PEM) electrolysis for hydrogen production has broad application prospects, but it still has disadvantages such as high equipment cost and insufficient durability. Optimizing the flow channel can improve the uniformity of water and heat distribution in PEM and extend the service life of the electrolyzer. To enhance the performance of PEM, a three-dimensional wavy flow channel model was designed and simulated using COMSOL simulation software. The polarization curves, distribution of reactants and products, and temperature distribution of electrolyzers with different frequency wavy structures were studied, and the influence of flow rate changes due to the addition of wavy structures on the performance of the electrolyzer was explored. The results show that, compared with the conventional rectangular flow channel, the electrolyzer with wavy flow channels has significantly enhanced the heat and mass transfer effects and got better polarization performance. When the wavy frequency is 1.0, the current density of the electrolyzer increases by 2.1%, and the average gas volume fraction in the anode catalyst layer decreases by 3.7%, achieving the best overall performance. This study can provide certain references for the flow channel design of PEM electrolyzers.