It is difficult to control NO_x emissions during full load operation of a 660 MW supercritical circulating fluidized bed (CFB) boiler in a certain power plant, and its instantaneous value is prone to exceed the ultra-low emission limit. In addition, the selective non-catalytic reduction (SNCR) system has a high ammonia consumption and severe ammonia escape issues. To solve these problems, on-site experiments on NO_x original emissions, SNCR denitrification efficiency, CO mass concentration and bottom slag combustibles were conducted, and optimization experiments on secondary air volume layout were also performed. It was found that, the original NO_x emissions of the CFB boiler were relatively low, with a maximum of 120 mg/m³ (standard condition) during full load operation and a NO_x mass concentration below 50 mg/m³ during medium and low loads. However, there was a significant deviation in NO_x mass concentration between the front and rear ends of the furnace, and the NO_x in flue gas was mainly generated in front of the furnace. The reason why NO_x emissions are difficult to control is due to the low denitrification efficiency of SNCR and uneven coal feeding in the furnace. The SNCR denitrification efficiency at inlet of the 6 separators was all below 50%, among which the denitrification efficiency of four separators B, C, E, and F was below 40%. Furthermore, according to the distribution of parameters in the furnace depth direction, such as the bed temperature, the content of combustible materials in bottom slag, and the variation of CO mass concentration, it can be determined that the uniformity of coal feeding in the furnace also had a significant effect on the control of NO_x emissions at full load. Currently, the power plant cannot achieve uniform coal feeding without renovation, but the original NO_x generation can be reduced by adjusting the secondary air volume ratio in the depth direction of the furnace, with a reduction of up to 9.77%.

Solar power plants can be complementary to other new energy power generation stations, and can also undertake the task of peak modulation and frequency modulation of power grid, which have attracted more and more attentions. In this paper, the dynamic simulation model of thermal storage system and power generation system is built and verified by Apros software. The coordinated control system of solar power plant considering the influence of heat storage is designed, and the maximum variable load rate of the solar power plant in different load intervals is studied. The results show that the proposed coordinated control strategy has a good control effect. Compared with the control without heat storage control, the deviation of main steam pressure with heat storage control reduces from 0.17 MPa to 0.07 MPa. Under the set limit conditions, the maximum load rise rate of 100%THA~75%THA load interval is 11.57%/min, and the maximum load reduction rate is 8.94%/min. The results can provide reference for peak shaving and frequency modulation operation of photothermal power plants.

In view of the increasingly serious problem of power grid peak regulation caused by the instability of new energy, combined with the relatively mature photo-coal complementary power generation technology and the multi-heat source combined heating peak shaving system, the light-coal mixed heating power generation system was designed to make the cogeneration unit have a certain peak regulation capacity. Based on the actual operating conditions of the heating unit and the premise of ensuring the heating load, the coupling mode of the solar-assisted dual-engine cogeneration unit was analyzed, and the peak regulation performance of the two-engine was compared before and after coupling. The results show that, a dynamic throttle valve is installed on the pipeline between the condenser outlet and the heat exchanger of the solar collector system, and the operation mode of the auxiliary heating unit of the solar collector system can be changed, which can realize flexible operation of the integrated system of power generation, heating and peak regulation. Among them, the solar thermal collection system is only used for supplementary heating, the peak regulation capacity ratio is 0.76, and the ratio of solar auxiliary double-heating supply before and after peak regulation capacity is 0.55. The No.1 unit which is assisted by solar energy to bear the maximum heating load has the best performance in peak regulation capacity and peak regulation compensation.

With the increase of various types of cyber-attacks, the security of industrial control systems in energy and power infrastructures has gradually become a focus of attention. Combined with the characteristics of power system, the CNN-LSTM-Attention network intrusion detection algorithm model integrating convolutional neural network (CNN), long and short-term memory (LSTM) neural network and Attention mechanism is proposed. By constructing and collecting the operating state data sets of the pulverizing system of a 600 MW coal-fired unit under three typical operating conditions under cyber-attacks in a laboratory simulation environment, the proposed detection algorithm model is trained and evaluated. The results show that, the proposed intrusion detection algorithm model has the best performance compared with the CNN and LSTM models. The model has the best rating indexes such as accuracy, precision, recall, etc., and the comprehensive evaluation is better than other intrusion detection methods. The intrusion detection algorithm model is highly innovative and practical.

Due to the characteristics of the medium transported by medium speed coal mill and the limitations of the inlet pipeline and space, the testing method under cold pure air conditions cannot guarantee the timeliness of the calibration test for the inlet air volume. Under hot conditions, the outlet pipeline of the coal mill was selected as test object for its stable flow field. The dynamic pressure and pulverized coal distribution characteristics of each powder pipe were tested by the equal cross-section grid method. The flow velocity of the air-powder mixture was obtained by the cyclic iterative method. Finally, the inlet air volume of the coal mill was compared and calibrated by the difference between the measured air-powder mixture flow rate, the coal quantity and the design sealing air volume. The practical results show that, on the basis of the same measured original data, the inlet flow rate obtained by the method above is closer to the real value, the accuracy can be improved by about 15 percentage points compared with the calculation results with cold conditions method. This method is simple to test and practical, which can effectively improve the timeliness and accuracy of the inlet air volume calibration results of medium-speed coal mill under hot conditions, and at the same time, it also has a certain guiding role in test of the flow rate of powder-containing gas in similar industrial environments.

ZnFe₂O₄ oxygen carrier (OC) doped with different additives (Sr, Ce, La and Al) was prepared by sol-gel method to investigate the influence of different additives on performance of the ZnFe₂O₄ oxygen carrier. Chemical looping hydrogen generation (CLHG) experiments were carried out in a fixed bed reactor. It was found that the performance of ZnFe₂O₄ was greatly improved by doping different metals, and the hydrogen production of per unit mass OC from high to low is La>Sr>Al>Ce. The physicochemical properties of different amount of La-doped ZnFe₂O₄ were further analyzed by combining X-ray diffraction, H₂-temperature-programmed reduction, Brunauer-Em-mett-Teller method and other characterization methods. The data indicated that the ZnFe₂O₄ modified by La with 12% mass fraction has the highest reaction activity. La dropping can increase the specific surface area of the OC, reduce the reduction temperature, increase the migration rate of lattice oxygen, promote the formation of oxygen vacancies, and is beneficial to the increase in hydrogen production in the chemical looping process.

Raw water pretreatment can be divided into three stages: coagulation, sedimentation and filtration. The flocculation process directly affects the structure of alum and the turbidity of effluent. At present, the method of measuring the turbidity of the effluent is usually used to control the dosage of coagulant, but due to the time lag, it can not quickly reflect the coagulation effect and adjust the dosage of the feedback. With the rapid development of computer technology, the application of alum image processing technology can realize rapid, accurate and real-time detection of flocs state, so as to control the dosage more accurately and improve the coagulation effect. From the perspective of computer vision technology, this paper summarizes the technical characteristics of alum image acquisition and processing in flocs, introduces the method of real-time tracking and calculating the characteristic parameters of alum structure, such as equivalent particle size, fractal dimension, etc., and some test results are also provided. Through these parameters the best coagulation effect can be judged, which provides the basis for coagulation control and dosing.

The HT700 superalloy was joined by rotational friction welding (RFW) method, and the welded specimens were subjected to post weld heat treatment (PWTH). The microstructural evolution and mechanical properties of the joints were systematically investigated by optical microscopy, scanning electron microscopy, transmission electron microscope, micro-hardness, and tensile tests at both room temperature and 750 ℃. The results show that, the as-welded joint shows three typical zones across the weldline: weld center zone (WCZ), thermomechanically affected zone (TMAZ), and heat affected zone (HAZ), in which the microstructure gradually changes from equiaxed fine grains (WCZ) and deformed coarse grains (TMAZ) to equiaxed grains (HAZ) that are similar to the base material. The dynamic recrystallization and dissolution of strengthening phases have occurred in the WCZ during RFW, in which γ′ strengthening phase dissolves to a larger extent than M23C6 or MC carbides. The microstructure of the as-welded joint including the grain size, shape, and the distribution of precipitates gradually changes from the weldline to the parent alloy. Consequently, the as-welded joints exhibit relatively poor mechanical properties due to the dissolution of γ′ which becomes even worse at 750 ℃ because of the grain-boundary sliding. After PWHT, the as-welded microstructure can be homogenized by grain growth and the re-precipitation of strengthening phases, which is responsible for the remarkable improvement in tensile strength at both room and high temperature after PWHT. And the high-temperature ductility of PWTH joints has been improved to a certain extent. This study gives new insights into the high-quality welding of the HT700 superalloy.

In order to realize efficient and accurate detection of the pitch bearing tooth surface of wind turbines in service under the adhesion of high viscosity lubricating grease, profiling array eddy current technology is used to study the effects of different coil arrangement methods and lifting distances on the detection results of bearing tooth surface defects. It can be concluded that, the edge effect range of Z-shaped and composite coil layout is different, and the composite profiling probe is significantly shorter than the Z-shaped probe. By detecting the artificial groove defects of 10.00 mm×0.50 mm×1.00 mm (slot length × slot width × slot depth), it indicates that the lifting distance limits for inner and outer toothed bearings are 1.04 mm and 1.43 mm, respectively. Experimental verification is conducted on the in-service fan bearings under the condition of high viscosity lubricating grease on the surface, and the results of defect size and position detection are accurate, with an error of less than 5%. This provides technical support and new ideas for supervision and inspection of the pitch bearing gear tooth surface in service.

In 2021, China launched its national carbon market. To enhance the accuracy of carbon trading, it is essential that carbon emission data are measurable, reportable, and verifiable. Against this backdrop, online monitoring systems for flue gas have gained significant attentions as a method of quantifying carbon emissions. The basis for the effective work of continuous emission monitoring systems is the accurate measurement of flue gas flow. However, the challenge in accurately measuring flue gas flow rates is significantly heightened by the large size of power plant chimneys and the complexity of the gas flow characteristics within them. This paper focuses on analyzing the current research status of Pitot tube flowmeters and ultrasonic flowmeters in large-scale duct flow measurement, and provides a detailed introduction to gas flow measurement technologies for large-scale ducts. Additionally, it introduces an independent flow measurement method, namely the tracer gas dilution method, and discusses its current development and potential as a flow calibration method.