In view of the frequent failure of power generation equipment under the background of frequent deep peak regulation, flexible operation, energy saving and consumption reduction of thermal power units, a coal mill fault warning method based on multiple state estimation-analytic hierarchy process is proposed. Firstly, based on the characteristic parameters of coal mill Spearman correlation analysis for dimension reduction, equidistant sampling method is used to extract some samples from a large number of coal mill history data memory matrix, after normalization, memory matrix is formed. Then, multi-state estimation algorithm is adopted to calculate the corresponding memory estimated vector according to the memory matrix and the observation vector. The characteristic parameters are given different weights by using analytic hierarchy process (AHP), and the fusion similarity between the observed vector and the estimated vector is calculated, and the fault warning of coal mill is carried out based on the adaptive threshold method. Finally, the actual fault data of a roller medium speed coal mill is taken as an example to verify the effectiveness of the method. The results show that, this method has less misalarm rate and false alarm rate for coal mill fault warning, which can reduce the actual fault probability of coal mill to a certain extent.

In order to effectively prevent the slagging of a supercritical 650 MW opposed firing boiler, the influence of different coal types on the flue gas temperature at the furnace outlet and the heat load of the boiler was checked by thermodynamic checking calculation, and the influence of the air distribution in the furnace and the cone-expanding angle of the burner on the flue gas dynamic field and flue temperature of the furnace was analyzed by CFD simulation. The results of the thermodynamic checking calculation showed that the boiler and the coal type were not the main reason for slagging. The variable air volume simulation showed that adjusting the ratio of internal and external secondary air could have effect on the dynamic field of flue gas. But in operation, changing the air volume did not solve the slagging problem well. The simulation results pointed out that the heat load of the water wall area could be reduced by reducing the cone-expanding angle of the burner from 45°to 30°, so as to inhibit the slagging. In the actual adjustment, after changing the cone expansion angle of the burner from 45°to 30°and adjusting the air distribution, the slagging situation of the boiler was greatly improved.The calculation results of variable SOFA wind showed that the appropriate reduction of SOFA wind proportion could reduce the flame height and the flue gas outlet temperature. The simulation of variable secondary air rotation showed that the secondary air rotation had a significant influence on the flow field and the slagging risk would significantly increase if the rotation of the burner was not arranged according to designed value. Further adjustments to SOFA wind ratio and secondary wind swirl could be considered in following adjustments.

In the context of energy transition driven by "carbon peak and carbon neutrality", an adaptive PID control algorithm in frequency domain is proposed to solve the quality problem of steam turbine back pressure regulation caused by frequent change of operating conditions in flexible air-cooled thermal power units. Considering the practicality and accuracy of the variable working condition model, on the basis of the site operation data, the improved particle swarm optimization (PSO) algorithm is used to identify the dynamic system of multiple working conditions of the air cooling unit. Then, based on the nominal model of the controlled object operated under multiple working conditions, the transfer function configuration mode adaptive method is employed to calculate and optimize the parameters of PID controller in real time, thus to adapt to the change of model parameters of the controlled object under flexible operation and overcome the control quality problems caused by PID controller structure and fixed parameters. The simulation results show that, the adaptive PID controller in frequency domain can well track the variation of model parameters under different load conditions, which makes the back pressure control keep good control quality.

A field test of paper mill sludge and coal co-firing was conducted on a 600 MW unit boiler to explore the effect of mix-firing sludge on the formation and emission of dioxins (PCDD/Fs). Under the conditions with and without sludge co-firing, flue gas samples at the inlet and outlet of drying-charring machine, the inlet of selective catalytic reduction (SCR) equipment, the outlet of air preheater and chimney as well as solid samples including raw sludge, dried and partly charred sludge, slag and fly ash were collected, and the PCDD/Fs were analyzed by a high-resolution gas chromatograph combined with high-resolution mass spectrometer. The obtained results indicated that, co-firing sludge (accounted for about 1% (weight percent) of pulverized coal) did not result in the formation of PCDD/Fs via high-temperature gas-phase homogeneous formation mechanism and medium- and low-temperature catalytic formation mechanism, and did not increase the emission of PCDD/Fs to atmosphere. The international toxic equivalence quantity (I-TEQ) concentrations of 6 chimney gas samples collected under the condition with sludge co-firing were in the range of 0.008~0.013 ng/m³ (average value: 0.010 ng/m³), which did not significantly differ from that (0.008~0.015 ng/m³, average value: 0.012 ng/m³) of the 6 chimney gas samples collected under the condition without sludge co-firing. It was found that, a small quantity of PCDD/Fs was formed during sludge drying-charring process. The newly-formed and original PCDD/Fs in sludge could be completely destroyed by high temperature in coal combustor. The SCR catalyst induced the catalytic degradation of PCDD/Fs, especially the highly-chlorinated dioxins. The concentration of the PCDD/Fs in fly ash samples were lower than 0.2 ng/m³, indicating its resource utilization could not pose dioxin pollution risk to ambient environment.

The existing GIS disconnector contact state evaluation method is based on the single state characteristic quantity, the reliability of the evaluation result is low, and it is easy to misjudge and erroneous judgment. So a method of GIS disconnector contact state evaluation based on multi-feature fusion was presented. The multi state quantity comprehensive detection experimental platform of 220 kV GIS disconnector was built. And the relationships between the GIS disconnector shell temperature signal, shell vibration signal, partial discharge signal and the contact state of the disconnector were experimentally studied. On this basis, the temperature rise of GIS disconnector shell, the amplitude of shell vibration signal and the discharge amplitude of partial discharge UHF signal were taken as the state characteristic quantities of disconnector, and the contact state evaluation model of disconnector based on support vector machine was established. The test results show that the accuracy of GIS disconnector contact state evaluation method based on multi-feature fusion is the highest, can reach 92.92%.

During the operation of selective catalytic reduction (SCR) flue gas denitration system of coal-fired units, NH₃ and SO₃ in the flue gas generate liquid ammonium bisulfate (ABS) at a specific temperature, which is viscous and easy to cause catalyst deactivation at 0~40% low load due to micropore plugging and aggravate the fly ash blockage of heat exchange elements at the cold end of air preheater. Alkali powder injection to remove SO₃ from flue gas is an important method to control ABS. However, the existing grid type multi-nozzle device has problems of uneven injection and low SO₃ removal efficiency. A vertical gas-solid fluidization mixing and distribution injection device is developed to improve the uniformity of absorbent powder injection in the flue section. The pilot test results show that, the SO₃ removal efficiency at upstream of the SCR denitration system reaches 55.6%, the condensation temperature of the catalyst ABS decreases by 8.6 ℃, and the minimum operation temperature decreases by 11.9 ℃, which can expand the lower limit of the catalyst operation temperature and reduce the restriction on the lower limit of the peak load of the unit. The SO₃ removal efficiency at upstream of the air preheater reaches 84.3%, and the ABS deposition influence coefficient decreases by 86.9%, which can delay the ABS ash blockage at the cold end of the air preheater. The SO₃ emission mass concentration from the chimney is 2.5~3.4 mg/m³, which can eliminate blue smoke.

The denitrification effect of coal-water slurry pyrolysis gas is investigated by numerical simulation in a 330 MW power station pulverized coal boiler, focusing on the influence law of excess air coefficient α₁ in the primary combustion zone (PCZ) and pyrolysis gas ratio β on the combustion characteristics and NO_x emission in the furnace. The results show that, when β is kept constant, the temperature of the PCZ decreases and the temperature of over-fire air (OFA) zone and furnace outlet increases as α₁ decreases. Meanwhile, the decrease of α₁ enhances the reducing atmosphere in the PCZ, which is beneficial to improve the denitrification rate of pyrolysis gas and thus to reduce the NO_x mass concentration at the furnace outlet. But the decrease of α₁ will affect the combustion performance of the pulverized coal and increase the CO concentration at the furnace outlet. With the increase of β, the center of the furnace flame moves up and the reduction rate of NO_x by pyrolysis gas increases. When β increases from 5% to 20%, the overall mass concentration of NO_x in the furnace shows a trend of first decreasing and then increasing, and when β=15%, the NO_x mass concentration reaches the lowest and the NO_x reduction efficiency of the pyrolysis gas reaches 44.35%.

Based on the dynamic vibration absorber method, analysis on abnormal vibration of vertical condensate pump motor and vibration reduction measures are carried out. According to the vibration characteristics of the condensate pump motor, the design method of power vibration absorption is studied theoretically, and the power vibration absorber is developed and designed and applied to the actual unit. The results show that, the dynamic balancing method has certain limitations in alleviating the vibration exceedance of the condensate pump motor during varying frequency operation, and cannot reduce the vibration amplitude of the condensate pump motor in both directions at the same time. The mass participating in the vibration of the condensate pump system shows a growing change with the increasing additional mass, and the first-order vibration mass at the top of the condensate pump motor is about 6 000 kg (X direction) and 7 000 kg (Y direction). With mass ratio of 2%, 5% and 10%, the maximum vibration amplitude in X direction is reduced by 80%, 83% and 86%, and the maximum vibration amplitude in Y direction is reduced by 68%, 77% and 83%. The dynamic vibration absorber device effectively reduces the vibration in both directions, and the actual reduction of vibration in X and Y directions is about 53% and 66% during the whole frequency operation period. The vibration control method based on the dynamic vibration absorber of the condensate pump motor has an excellent vibration reduction effect.

Against the difficulty of optimal scheduling of integrated energy systems under the operating conditions of multiple energy complementary mechanisms, a multi-objective optimal scheduling study is carried out considering the reduction of system operation and maintenance costs, carbon dioxide emission and renewable energy abandonment. A mathematical model is established for all the equipments in the electric-gas-heat-cold energy system. The constraint conditions that can simulate the long-term operation scheduling of the integrated energy system are established to solve the modeling difficulties of energy storage equipment in the long-term operation simulation, and the comprehensive energy system is optimized by using low-carbon economic operation index. The results of the minimum operation cost scheduling and the minimum carbon emission scheduling are compared. Moreover, the influence of carbon price and operation and maintenance cost increase on scheduling results is simulated. The simulation results show that, using only the minimum operation and maintenance cost or the lowest carbon emission as the scheduling index will lead to high carbon emission or high operation and maintenance cost, and the low-carbon economic scheduling considering the consumption of renewable energy and carbon emission reduction index can reduce the low-carbon economic operation cost of the whole system.

In order to reduce the air and pulverized coal distribution deviation of pulverized coal system, optimize the boiler combustion condition and expand the application range of pulverized coal distributor, a new pulverized coal distributor needs to be developed. By means of test bench model test, a new type pulverized coal distributor is developed. The structural design of the distributor model is completed, and the key performance of the distribution is studied, such as the effects of the pulverized coal distributor's coal amount damper resistance characteristics, the air and pulverized coal distribution and regulating characteristics, and resistance regulation on the distribution characteristics, as well as the effect of system air speed on the distribution characteristics. The results of model test and engineering application show that, the new pulverized coal distributor can effectively control the air volume deviation of the pulverized coal delivery pipeline within ±5% and pulverized coal deviation within ±10%. After the engineering transformation and leveling test of the new pulverized coal distributor for No.3 boiler of a power plant, the thermal load deviation of furnace can be effectively reduced, and the deviation of the two metal wall temperature points, which can reach 150 ℃ before transformation, can be controlled within 15 ℃, which greatly improves the safety and reliability of the boiler operation. The development and engineering application of the new pulverized coal distributor have certain guidance and reference significance for reducing the distribution deviation of pulverized coal in pulverized coal system and solving the series of problems such as partial burning, over temperature and corrosion in boiler operation.