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%.

"Three-renovation" (energy-saving renovation, flexibility renovations and heating renovations) of coal-fired power is an effective measure for clean and low carbon utilization of coal. The paper analyzes current energy efficiency, flexibility and heating situation of coal-fired power, and researches the policy requirement, implementation progress and expected effect of "Three-renovation". In terms of technical difficulty, energy saving renovation is the most difficult, followed by flexibility and heat supply. It is anticipated that the coal consumption for power supply will be decreased to about 297 g/(kW·h), the additional peak regulation capacity will be over 40 GW and the heating scope will be further expanded. In view of the problems such as large coal power loss, difficult technical transformation of some types, hidden safety risks of equipment under low load operation, unanticipated input and output of renovation, and small financial support of renovation, this paper puts forward measures and suggestions to promote the "Three-renovation" from the perspectives of policy, technology, standards and market.

In order to realize the cold end optimization of direct air-cooled units, a cold end operation optimization method of air-cooled units is proposed based on the historical operation data of units and combined with data mining and deep learning algorithm. Firstly, the obtained historical operation data are screened in steady state and divided into working conditions. Combined with the Gaussian mixture model algorithm, the back pressure reference interval of the unit under multiple working conditions is determined. Then, the Spearman coefficient method is used to select the characteristic variables, and the back pressure prediction model of the direct air cooling unit is constructed in combination with the gated circulation unit. The back pressure optimization suggestions and early warning information are given by comparing the back pressure reference interval with the back pressure prediction value. Finally, the method is applied to a subcritical 300 MW air-cooled condensing steam unit. The results show that the back pressure optimization method proposed in this paper can give effective back pressure early warning information and realize optimal operation of cold end of the air-cooled unit.

At present, the self-provided power plant has a large generating power, which can not be ignored in the future new energy grid-connected peak regulation. According to the selected factory-owned power plant with power and heat supply, there are the low-pressure cylinder zero output scheme, high back pressure extraction combined exhaust steam heating scheme, absorption heat pump and compression heat pump scheme. four thermo-electrolytic coupling schemes are quantitatively calculated and evaluated to provide guidance for the selection of decoupling schemes for factory-owned power plants. Four schemes were used to optimize the case unit, and the calculation results showed that after decoupling, the heat supply of the heating extraction stage can be separately increase 174.00 MW, 136.18 MW, 168.37 MW and 38.00 MW. The minimum electric load rate was reduced to 44.29%, 73.29%, 73.70% and 80.57%. The maximum heat-to-electricity ratio reached 2.00, 1.50, 1.50 and 1.15. The zero-output decoupling effect of the low-pressure cylinder is the most obvious, the maximum heat supply increases the most, and the electric load rate decreases the most. Economic analysis shows that the absorption heat pump scheme has the most increased investment cost compared to other schemes.

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.

Turbine cooling system is one of the cores of modern heavy-duty gas turbines. How to consider the influence of cold gas admixture is one of the first problems to be solved in gas turbine thermodynamic modeling and analysis of the influence of key parameters. With the continuous deepening of overall design of the gas turbine, a more detailed thermal performance calculation model is required to coordinate and match key components and the whole and ensure the final realization of the design performance. A calculation method of step-by-step blending and overall thermal performance of gas turbine based on one-dimensional aerodynamic analysis of turbine is proposed, and a thermal performance model of heavy-duty gas turbine is established. Moreover, the influence and key parameters and thermodynamic performance scheme of G/H class gas turbine is investigated. The analysis shows that, the turbine initial temperature, pressure ratio and cooling air volume are the key parameters affecting the overall thermal performance of the gas turbine, and the three should be coordinated in the overall design. While improving the turbine initial temperature, the minimum cooling air amount required to reach the temperature level should be studied, the optimal pressure ratio should be analyzed, and the iterative calculation and thorough research should be confirmed after combining the component design. The research results can provide a reference for the overall performance design of autonomous heavy-duty gas turbines.

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.

In order to effectively deal with the complex electricity and coal market, strengthening the smart fuel management has become an important part of thermal power plant management. Aiming at solving the problems that the coal yard of a coal-fired power station occupies small area, the types of incoming coal are complex, and the coal-fired coal stacking is chaotic, by extracting the coal quality information of historical incoming coal, K-means and DBSCAN clustering algorithms are used to analyze the low-level coal. The calorific value, volatile matter and sulfur content are clustered and analyzed, and the two clustering algorithms are compared from the perspective of silhouette coefficient, cluster stability and sample division fineness, and finally K-means with better clustering effect is selected as the calculation method for coal quality division. The K-means algorithm divides the selected historical coal quality information data set into four categories, the contour coefficient is 0.587, and the coal quality components in each category are similar. The incoming coal frequency and the incoming coal weight ratio under different cluster labels are counted, and the coal yard is divided into corresponding proportions. The incoming coal of the same classification is stacked in each partition, and on this basis, the incoming coal in the digital coal yard platform is designed. Coal stacking guidance and information storage process are of great significance to improving the utilization of storage yard space and the efficiency of coal yard management.