To improve steam parameters for better power generation efficiency and economy and meet the development needs of nuclear power plants, a duct-type steam generator is proposed, which is suitable for high-temperature gas-cooled reactors with ultra-supercritical parameters. The main features of the duct-type steam generator’s structure are introduced, and the advantages of this structure in terms of heat transfer performance, operation safety, and production cost are analyzed. Through the establishment of a theoretical calculation model, thermal engineering analysis and heat transfer performance study of axial, radial, and quasi-three-dimensional temperature distributions and other parameters of the steam generator with direct countercurrent heat transfer mode are carried out. The calculation results show that, the duct-type steam generator is mainly based on convection heat transfer mode, with obvious temperature distribution segments and excellent heat transfer performance, which meets the relevant heat transfer requirements. This study can provide a reference for design and development of steam generators in nuclear power plants.

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.

Under deep peak shaving and variable operating conditions of thermal power units, significant changes in steam temperature have caused a significant increase in thermal stress in some structures of the units, which accelerated structural damage, and resulted in frequent safety accidents. To solve these problems, by taking the regulating stage rotor of a 300 MW steam turbine as the object, and Ansys software is used to analyze the thermal stress, aerodynamic force, and centrifugal force of the blades. Firstly, structural optimization is carried out on root of the blade to significantly eliminate the unreasonable local stress concentration phenomenon commonly found in conventional calculations. Then, the distribution laws of temperature and stress fields in the regulating stage under different conditions such as steady-state and transient during the deep peak shaving process of thermal power units are revealed. Moreover, the effects of the temperature and stress fields on safety performance of the unit are also investigated. The results indicate that, the maximum equivalent stress increases by about 24% under steady-state conditions with temperature difference of different nozzle groups of 50 ℃. The transient load increase rate of 5% THA/min is about three times higher than that of 2% THA/min, causing low cycle fatigue damage to the rotor. Compared with steady-state operating conditions, increasing the load once a day at a rate of 2% THA/min from half load to full load increases the overall damage by about 38%.

To improve the accuracy of carbon emission accounting and make the effect of carbon emission reduction more intuitive, it is proposed to associate power plant generation with carbon emission intensity. Firstly, the carbon emission performance of the gas-steam combined cycle unit is calculated based on Aspen Plus. Then, the carbon emission performance is analyzed from the aspects of four influencing factors: unit load, environmental temperature, heat network input and natural gas composition. The results show that, the established Aspen Plus model can simulate the operation of the power plant accurately. Taking the S106FA multi-axis gas-steam combined cycle unit of a power plant as an example, the calculated carbon emission performance is 342.66 g/(kW·h). The carbon emission is calculated by comparing the measured method and the emission factor method. The carbon emission performance accounting is closer to the measured method, and the deviation between the carbon emission performance method and the measured method is 0.20%. The deviation between the measured method and the emission factor method applying the measured low calorific value and the saved and deficient low calorific value are 5.24% and 19.66%, respectively. Unit load has the most obvious effect on carbon emission performance of the combined cycle unit, followed by heat network input, ambient temperature and natural gas composition. To reduce the carbon emission performance of the combined cycle unit, the power plant needs to arrange the peak regulation time and heat network heating reasonably, and using renewable energy as an alternative or supplementary fuel can be considered.

For the integrated energy system composed of photovoltaic power generation, energy storage battery storage and discharge, and coal-fired heating boiler and cogeneration, the power and heat power systems operate in isolation. To analyze the relationship between the information interaction and economic coordination and dispatch of the integrated energy system, by using the J.F.Benders mixed variable target decomposition method, the physical model of the cogeneration photovoltaic storage thermal power system is decomposed according to the main thermal system and the power subsystem. The information interaction between the sub-objectives is analyzed by the objective function and the system boundary conditions, and the mathematical model of the coordinated scheduling operation of photoelectric consumption and storage and cogeneration is obtained. The protection information is isolated and redirected, and the multi-dimensional variable problem of mixed integer programming is iteratively calculated by Gurobi solver. Based on the case of the integrated energy system, three operating conditions under different load requirements of power and heat are analyzed, and it is found that, the economic benefits of the thermal power operation system are synergistic and complementary, and the information interaction expands the space for photovoltaic consumption. The net load of the system reduces by 13.63% on average, the interactive power loss decreases by 9.480 7 million yuan/year, and the energy utilization efficiency rises by 4.48 percentage points, which shows that this model can serve the economic coordination and scheduling optimization and energy efficiency improvement of the integrated energy system.

To accommodate grid-connected large-scale renewable power, coal-fired power plants need to undertake more peak shaving and frequency regulation tasks, so it will engage in the processes of deep peak shaving and load cycling for a long time. In this situation, the performance of wet flue gas desulfurization system (WFGD) will degradation and the auxiliary power consumption will increase significantly. To solve this problem, the dynamic model of an ultra-supercritical 660 MW coal-fired power unit and the dynamic model of the WFGD system based on the double-membrane theory are established. The performance of the desulfurization system is simulated when the slurry circulation pumps are switched under different operating conditions during the load cycling processes. It is found that the precise matching of slurry and flue gas during load cycling processes can achieve the minimum power consumption of the desulfurization system while meeting the SO₂ emission standard. Furthermore, when the slurry circulation flowrate changes stepwise during load cycling processes, the prediction model of changes in SO₂ mass concentration at the WFGD system outlet is obtained. An optimization control strategy for the slurry circulation pumps in fixed-frequency mode is proposed, which can achieve the best match between the slurry and flue gas during load cycling processes. Finally, the energy saving potential for the proposed control strategy is analyzed. When the load cycling rates are 1.0%, 1.5% and 2.0% Pe/min, the energy saving potential is 20.12%, 21.52% and 22.82% during loading down processes from 75% THA to 50% THA conditions, and that value will be 10.04%, 9.90% and 8.66% during loading up processes, respectively. The difference in flue gas flowrate during load cycling processes is found as a key factor causing the disparate of energy saving potential during loading down and loading up processes.

Decarbonization in thermal power industry is directly related to the realization of the “double carbon” target, while the circulating fluidized bed boiler has the advantages of wide fuel applicability and can carry out large-scale fuel blending. Biomass fuel is a renewable “zero-carbon” energy source, its blending can greatly reduce the carbon emissions of thermal power plants. Based on the existing circulating fluidized bed boilers and coal-fired conditions, biomass co-firing tests were conducted, and comprehensively evaluation was also carried out on combustion stability, pollutant emissions, and thermal efficiency. The co-firing experiments results showed that, as the co-firing ratio increased, the coal consumption rate per unit of steam production significantly decreased, with stable combustion conditions maintained throughout the process. Under co-firing conditions, the consumption of limestone decreased to approximately 4.5 kg for 1 ton steam production, with SO₂ emissions meeting the standards. Blending raised the furnace temperature, elevated the exhaust temperature, increased the fly ash content, and slightly increased the heat loss. Through regulating the air volume ratio, material layer pressure difference and excess air coefficient, the overall thermal efficiency closely approached the design value. Under long-term operating conditions, the blending ratio of biomass reached about 30%, and the emissions of SO₂ and NO_x were qualified. The tail heat exchanger was not corroded obviously, and the CO₂ emission reduction amount reached about 480 kg for 1 ton steam production.

Due to factors such as coal quality and combustion, coarse fly ash particles in flue gas of coal-fired boiler can easily cause varying degrees of wear and tear on tail flue and denitrification catalysts. An “A-V-T” type pre-removal structure for coarse particle fly ash before denitrification is established using the flue from the economizer outlet to the denitrification system inlet of a 300 MW unit as the research object. The structure is composed of “A-type baffle enrichment + V-type high-efficiency ash collection + T-type coarse ash channel” and is placed in a large cross-section low flow velocity flue at the economizer outlet. The influence rules of different particle size distribution trajectories, removal effects and resistance before and after the arrangement of the coarse particle fly ash pre-removal device are studied through numerical simulation, and engineering application is conducted to verify the effectiveness. The numerical simulation results indicate that, the use of coarse particle removal technology has little effect on flow field state of the original system at flue gas side. As the particle size of fly ash increases, the removal rate of fly ash increases. The removal rates of fly as particles with size of 50, 200, 500, and 1 000 μm are 12.15%, 59.40%, 87.01%, and 93.62%, respectively. The removal efficiency for coarse particles with size of 200 μm and above is 85.15%. The overall ash collection rate is 15.50%, with an additional resistance of 78 Pa. For this 300 MW unit, the tests after retrofitting show that, the removal rate of coarse ash particles with size of 200 μm and above is 83.96%, the overall removal rate of ash is 14.91%, and the net increase in resistance is 73 Pa. The experimental results verify the rationality of the numerical simulation results.

With the increasing penetration rate of renewable energy in China’s power system in the future, the stability of the system will face more severe challenges. Long-term energy storage technology plays an important role in balancing grid demand, improving grid stability, promoting the consumption of renewable energy, and promoting green and low-carbon development in the power system. Long-term energy storage has a wide range of application scenarios on the power supply side, grid side, and load side of the system, which is of great significance for the development of China’s new power system. Firstly, the characteristics and development trends of the current new power system are introduced, and the supporting role of long-term energy storage technology in the new power system is analyzed. Then, the technical principles and routes of five long-term energy storage technologies, such as the compressed air energy storage, lithium-ion battery energy storage, liquid flow battery energy storage, molten salt energy storage, and hydrogen energy storage, are summarized. The advantages and disadvantages of various long-term energy storage technologies are also analyzed. Finally, the future application prospects of long-term energy storage technology in the new power system are discussed.

The compressed air energy storage is a large-scale physical energy storage technology and a highly promising new type of energy storage technology. This paper summarizes the basic principles of isothermal compressed air energy storage, and introduces the principles and current development status of key equipment and related technologies. It provides an analysis and summary of liquid pistons, pumps and turbines. Moreover, it reviews the basic principles of isothermal compressed air energy storage, and analyzes the existing research progress on isothermal compressed air energy storage technology. An analysis and summary are presented for liquid piston technology, as well as pump and turbine technology in the system. The data of existing compressed air energy storage power stations are summarized and analyzed. The data of existing compressed air energy storage power stations are summarized and analyzed. On this basis, the future development direction of isothermal compressed air energy storage technology is prospected, which provides a certain data reference for the selection of power equipment in isothermal compressed air energy storage system and the promotion of demonstration projects.