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.

In order to improve the cooling performance of cooling tower, this study takes a 300 MW unit cooling tower in the north as an example, establishes a 3D numerical calculation model of cooling tower, compares the effect of non-equal packing in two and three zones on the outlet tower water temperature, determines the optimal radius dividing point, and cooperates with non-uniform water distribution for optimization, analyzes the effect of different optimization schemes on the air flow rate, tower water temperature and ventilation volume in the outlet tower. The results show that the cooling performance is improved with the exit tower water temperature of 31.798 ℃and 31.696 ℃ under the non-equally spaced packing in the second and third divisions, respectively. The coupling optimization of non-equally spaced packing with non-uniform water distribution significantly improves the uniformity of aerodynamic and temperature fields. With the increase of water distribution in the inner zone, the outlet water temperature and ventilation volume both show a trend of first increase and then decrease, and the optimal water distribution in the inner zone is 50%, and the outlet tower water temperature is 31.36 ℃ and ventilation volume is 7 122.8 kg/s. Compared with 26 mm and 30 mm equidistant packing arrangement, after collaborative optimization, the water temperature of the tower is reduced by 0.768 ℃ and 0.83 ℃, respectively, and the cooling performance is significantly improved.

The effects of different heat transfer fluid (HTF) parameters on charging and mechanical performance of the thermal energy storage (TES) tank using phase change material (PCM) capsules are studied by employing the fluid-solid coupling calculation. The results show that, with the inlet HTF flow velocity increased from 0.000 7 m/s to 0.000 9 m/s, the total heat storage quantity is basically unchanged, the average charging power increases from 5.33 MW to 6.79 MW, and the peak maximum mechanical stress (MMS) of the tank wall decreases. When the initial cold HTF temperature decreases from 610 K to 530 K, the total heat storage quantity increases, the average charging power increases from 5.29 MW to 6.81 MW, but the peak MMS of the tank wall also increases. With the initial hot HTF temperature increases from 730 K to 810 K, the total heat storage quantity increases obviously, the average charging power increases from 3.81 MW to 7.97 MW, but the peak MMS also increases to 159.6 MPa. Hence, to improve the charging performance of the TES tank, on the premise of ensuring the structural safety of steel wall of the TES tank, the inlet HTF flow velocity and initial hot HTF temperature should be increased properly, and the initial cold HTF temperature should be reduced properly.

In order to avoid disrepair and overrepair, improve the reliability and availability of gas turbine, reduce operation and maintenance cost, and ensure its safe, stable, green and efficient operation, a novel approach is proposed for fault diagnosis of gas turbine in power plants under transient operating condition with variable geometry compressor. The mathematical relationship of the influence of the compressor inlet guide vane position on compressor flow and efficiency characteristics is deduced. A high-precision thermodynamic model for the purpose of performance analysis and gas-path fault diagnosis is established. Moreover, the gas path fault diagnosis strategy of power plant gas turbine, which is suitable for transient and variable conditions and includes variable geometry, is proposed. Through actual operation test, it is verified that the proposed method has high diagnostic accuracy and good real-time performance, and the fault identification under transient and variable conditions is realized.

Frequency conversion condensate pump is easy to produce structural resonance because of insufficient support stiffness of vertical structure and increased working frequency range. According to the problem of excessive vibration in two resonance zones of a 350 MW vertical variable-frequency condensate pump, this paper introduces the principle and influencing factors of structural resonance, the judgment method of vibration fault and the treatment process. Theoretical calculation and actual treatment results show that, when there is unbalance on the shafting, dynamic balancing can effectively reduce the vibration amplitude in the resonance area of the condensate pump. However, when there are multiple resonance zones at the same time and the counterweight schemes corresponding to different resonance zones are contradictory, the dynamic balance mode cannot be considered at the same time. The angle of the counterweight determines the dynamic balance effect. Due to the limitation of the reserved counterweight angle, the rapid change of the vibration phase near the resonance point, inaccurate measurement and other factors, it is difficult to achieve on-site fine dynamic balance. Increasing the support to improve the system stiffness can change the natural frequency of the structure and reduce the vibration amplitude in the resonance area, which is an effective measure to solve the resonance problem. The vibration reduction effect of radial support is better than that of axial support.

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.

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.

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%.

Under the background of auxiliary heat supply of ejector, in order to study the characteristics of ejector under variable working conditions, the calculation methods of ejector at home and abroad are investigated, the ejector calculation model is established and coupled with the high back pressure unit. Moreover, the effects of working steam, ejected steam, ejector back pressure, and ejector opening on the performance of the ejector under variable working conditions are obtained. The results show that, when the working fluid pressure of the ejector changes from 0.25 MPa to 0.45 MPa, the mass flow of the working fluid first increases and then decreases, and the ejector has the best performance at the design working steam pressure. The critical back pressure increases with the steam injection pressure. The pressure of the mixed fluid after injection will not only affect the work of the ejector but also the work of the condenser. Compared with the back pumping unit, the minimum cooling flow of the low pressure cylinder of the high back pressure coupling injector unit can be reduced by 140 t/h and the power supply range can be increased by 43 MW.