The pH values of boiler feed water, steam, boiler water and other measuring points in a chemical power plant were abnormally low, and the problem could not be effectively solved by adjusting the boiler water dosing process. In order to solve this problem and ensure the safe operation of the unit, this paper discusses and analyzes the influence of water sample temperature on pH electrode, Nernst temperature coefficient slope and solution temperature coefficient (ionic activity), and verifies through experiments that the abnormally low pH measurement value is caused by the large deviation of water sample temperature from 25 ℃, and the pH measurement method cannot provide correct temperature compensation. Strict control of water sample temperature, adoption of computational pH meter or selection of high-precision pH meter with precise non-linear temperature compensation function can effectively solve the problem of abnormally low pH measurement in the water and steam system.

In order to accelerate the achievement of the goals of "carbon peaking" and "carbon neutrality", a series of laws, regulations, and institutional documents on greenhouse gas control have been introduced by the country, local governments, and industries. Nitrous oxide (N₂O), as a gas with strong greenhouse effects, has attracted increasing attention from researchers. This article summarizes the current research status of N₂O at home and abroad, compares the N₂O emissions of typical coal-fired boilers, analyzes the generation mechanism, influencing factors, suppression methods, and removal methods of N₂O during the combustion process, explores N₂O emission reduction strategies for coal-fired boilers, and provides suggestions. It is necessary to strengthen the formulation of N₂O related standards, research and development of new technologies, and demonstration applications for coal-fired boilers. Further research is needed on the influencing factors of N₂O, such as pressurized oxygen enrichment conditions and coal moisture content, to further improve the suppression and removal methods.

In the domestic large circulating fluidized bed boilers designed with side wall and back wall coal feeding system, there are generally prominent problems of coal feeding delay and uneven coal feeding in the actual operation process. By analyzing the coal feeding delay problem of large CFB boiler units and the operation characteristics of the existing coal feeding system, the quantitative calculation method of coal feeding delay problem of large CFB boiler coal feeding line is put forward. Based on the case of a supercritical 600 MW CFB boiler coal feed line, the coal feed delay characteristics of the coal feed line under the condition of wide load and rapid peak regulation are obtained. The calculation results show that the coal feed delay problem is common in the variable load operation process of large CFB boiler units, which will lead to a certain degree of uneven coal feed. The variable load range, variable load rate and the number of coal feed ports on the single feed line are positively correlated with the severity of the delay problem. The calculation method and analysis results can provide design basis and technical reference for large CFB boiler coal feed line to adapt to wide load and fast peaking operation.

In order to provide methodological guidance for the load optimal distribution of thermal power units under the condition of deep peak regulation, the objective functions of optimal load distribution under medium-high load and low load are established respectively, and the load optimal distribution under different conditions is studied. The k-means clustering algorithm is used to process the data and the coal consumption characteristic curves of two units under medium-high load and low load are fitted. The objective function of load distribution is established to compare the coal consumption before and after optimization under static load distribution, incremental load distribution and continuous variable load conditions. After setting the total load instructions of the two units under the condition of deep peak shaving, the coal consumption of the two schemes of load average distribution and optimal distribution is compared. The results show that the clustering-based objective function models of optimal distribution under medium-high load and low load established by the coal consumption characteristic curve are reliable, whose optimization effect is remarkable under the condition of deep peak regulation. The k-means clustering algorithm can be used to optimize the load distribution of thermal power units and provide reference for the study of load optimal distribution under the condition of deep peak regulation of thermal power units.

To provide guidance for the flexible operation of 350 MW supercritical CFB boiler, experimental investigations were conducted on the flow and heat transfer characteristics of water with low mass flux in vertical upward smooth tube under subcritical pressure. Flow and heat transfer experiments were performed under the conditions of 12~15 MPa pressure, 350~440 kg/(m²·s) mass flux, 135~220 kW/m² inner wall heat flux. Furthermore, the dynamic characteristics of the tube were experimentally studied by decreasing pressure and increasing inner wall heat flux, based on the 26 MPa heat transfer experiments. The results of the heat transfer experiments indicate that changing pressure affects the heat transfer performance and enthalpy range of the saturated boiling region. The influence of mass flux on heat transfer performance is only reflected in the sub cooled zone, and the heat transfer performance is enhanced with the increase of mass flux. Increasing heat flux decreases the heat transfer performance in the saturated boiling region. Meanwhile, the correlations of the heat transfer coefficient and friction resistance of water in the tube were fitted based on the experimental data. The dynamic experimental results show that the greater the pressure step, the greater the mass flux increment, and the greater the change in the outlet enthalpy and outlet wall temperature. The step of heat flux only affects the outlet enthalpy and outlet wall temperature. The greater the step of heat flux, the greater the change in the outlet enthalpy and outlet wall temperature. This work can provide guidance for supercritical CFB boiler in low load and flexible variable load operation.

Facing the frequency security problem caused by large-scale integrations of fluctuating new energy, the participation of thermal power units coupled with flywheel energy storage in frequency regulation can effectively improve the active power support capability of the power grid from the generation side, which is an effective guarantee for the frequency security of the power grid. According to the output control strategy and capacity configuration of flywheel energy storage systems, this paper proposed a combined method of flywheel control strategy and capacity configuration for primary frequency regulation to optimize the thermal power unit operations. Firstly, a coordinated frequency regulation control strategy of flywheel energy storage considering the real-time power output of thermal power units is designed. An economic evaluation model considering the primary frequency regulation benefit of power plants is proposed, and a refined particle swarm optimization algorithm is utilized to tackle the problem. Finally, the actual data of a 315 MW unit in a power plant from the northern part of China are simulated and verified. The result shows that the proposed integrated configuration strategy can effectively improve the frequency modulation effect of the power grid while taking the cost of energy storage investments into account. The research results are of great significance for promoting engineering applications of flywheel energy storage participating in frequency regulation services.

In order to solve the problems of user account management and security protection in current group information system, this paper proposes a three-in-one AAA system of account, authentication and audit based on zero-trust architecture. Firstly, it describes the function of user management, authentication authorization, user audit and other modules of the AAA system. Secondly, in view of the conventional network boundary protection problem, the authentication authorization method based on zero trust architecture is applied to identify the business scenario, thus to ensure the reliability of the business system environment. Lastly, it illustrates the logic of the AAA subsystem and group-level system development platform configuration. The proposed AAA system can effectively improve the business security of group-level enterprise information system, compensate for the security issues of user login account under zero-trust environment, and further improve the security protection ability of network equipment, application equipment, system and application management in group-level enterprise.

The coupling of thermal units with flywheel energy storage system can effectively improve the frequency regulation performance of AGC, solve the problems of long response time, slow climbing rate and low regulation accuracy of thermal units when tracking AGC commands, and obtain the auxiliary revenue of frequency regulation. This paper proposes a flywheel energy storage system control strategy for engineering practice, taking into account the requirements of the "two rules" of the Northwest Power Grid on AGC climbing performance, to improve the performance index of the combined system participating in AGC frequency regulation while preserving flywheel power. The results show that the proposed strategy improves the performance of the combined thermal power units and storage systems in AGC, and the economic efficiency of the power plant is significantly improved.

In order to ensure that the supercritical CFB boiler has good wide-load operation characteristics and the ability of deep peak regulation, the transient heat transfer characteristics between the working fluid and the water wall under the change of transcritical pressure are experimentally studied. Experiment adopted Φ25.0 mm×3.5 mm vertical upward tube, the near-critical steady heat transfer experiment and the transcritical pressure step transient heat transfer experiment were carried out under the experimental conditions of 20~23 MPa of pressure and 400~800 kg/(m²·s) of mass flow rate. The results showed that under the near-critical pressure, increasing the flow rate, reducing the heat flux on the inner wall, and reducing the pressure can reduce the dryness when the DNB heat transfer deterioration occurs, and increase the corresponding fluid enthalpy value, and delay the occurrence of the heat transfer deterioration. When the transcritical pressure step changes, the heat transfer deterioration may occur in the heating pipe, resulting in the wall temperature rising rapidly, but the temperature will fall back to the normal value with the increase of the flow rate. The heat transfer between the wall temperature rising point and the inner wall surface goes through the heat transfer deterioration stage, the subcooled boiling heat transfer enhancement stage and the single liquid phase heat transfer stage. The influence of each parameter on the heat transfer deterioration in the transcritical pressure step change experiment is the same as that in the near-critical steady state experiment. The decrease of flow rate and the increase of heat flux on the inner wall will advance the location of the heat transfer deterioration, and the wall temperature rise will be greater.

The flue gas recirculation device in the conventional circulating fluidized bed (CFB) oxy-fuel combustion system has been taken out and replaced with pure oxygen combustion, which is expected to reduce the overall energy consumption and CO₂ capture cost of the unit. Pure oxygen combustion will bring about problems such as uneven distribution of heat load and fluidization difficulty under minimal smoke gas flow, so a new boiler design should be carried out according to the flow pattern and heating surface layout in the furnace. This paper adopts the arrangement of immersed tube heating surface in the dense phase area to solve the local over-temperature problem. At the same time, a unique furnace structure design of "wide at the bottom and narrow at the top", reducing the size of the bed material, increasing the primary air ratio and other methods are used to deal with the difficulties of material fluidization. Based on the CFB flow and heat transfer theory, a heat transfer calculation method of pure oxygen combustion CFB boiler is established, and a conceptual design of 130 t/h ultra-high pressure pure oxygen combustion CFB boiler is completed. The basic structure and overall layout scheme of boiler furnace, immersed evaporating heating tube, immersed superheater, cyclone, loop seal and economizer are given. Preliminary analysis shows that the new pure oxygen combustion CFB boiler can solve the problems of uneven distribution of heat load caused by high oxygen concentration combustion and the difficulty of material fluidization under minimal smoke gas flow. The designed boiler thermal efficiency can reach 94.83%, and the volume fraction of CO₂ and H₂O in the outlet flue gas is 57.1% and 38.4%, respectively. This paper lays a foundation for the future development of pure oxygen combustion CFB boiler technology and engineering practice for CCUS-EOR.