In order to clarify the dynamic characteristics of bed temperature of biomass circulating fluidized bed (CFB) boiler, so as to establish a CFB combustion control system which is more suitable for biomass, a dynamic bed temperature model is established by analyzing the biomass combustion process and combustion mechanism. On the basis of the theory of instant burning carbon combustion, the correlation degree of temperature field in the furnace is calculated and analyzed. The results show that, the calculated bed temperature can be controlled basically stable near the filtering value of the actual bed temperature, and the variation trend of the bed temperature is similar to that of the actual filter bed temperature, which verifies the adaptability and effectiveness of the model. The temperature correlation difference of the upper and lower parts of the biomass CFB boiler is related to the oxygen content and the temperature of the furnace. The temperature difference of the left and right sides is greatly affected by the flue gas flow. In the upper part of the furnace, the material concentration and the uneven heating surface arrangement are also important reasons affecting the temperature characteristics.

Using ceramic membrane to recover moisture from gas is a feasible way that not only can realize the recycling of resources, but also can alleviate environmental pollution. By taking double-row ceramic membrane module as the research object, the heat and mass transfer of water vapor transport was theoretically analyzed, the physical model was established, and numerical simulation was carried out according to the boundary parameters under actual conditions. Then, a pilot test platform was built on a coal-fired unit to carry out the experimental research on the purified flue gas after wet desulfurization. The results show that, the amount of recovered water decreased linearly from 29.45 kg/h to 18.13 kg/h by increasing the cooling water temperature from 25 ℃ to 36 ℃. With the growing of flue gas flowrate, the recovered water gradually increased, but the growth rate gradually decreased. The deviations of the recovery water amount between the calculated results and the experimental data were less than 7%.

Based on the elastic beam theory, a theoretical calculation model for the axial force of the in-service tie rod under transverse loading conditions and the three-dimensional finite element model of the prestressed beam are established. The axial force measurement method of the tie rod of the in-service support hanger is studied, and the influence of different length-to-diameter ratios and transverse loads on the deflection of the midpoint for the tie rod are discussed. The results show that the theoretical prediction results are in good agreement with the finite element calculation results. In terms of engineering applications, an optimal scheme for the length-diameter ratio of the fixed support section of the tie rod is given based on the transverse load tolerance and deflection tolerance value. This method can be used to quickly measure axial load of tie rod when it is not uninstalled.

Combined heat and power (CHP) units are affected by the output fluctuation of large-scale operating conditions, resulting in poor overall control quality of power generation load-extraction steam flow-throttle pressure in the turbine-boiler coordinated control system. To solve this problem, a multi-condition adaptive control method based on multi-agent deep deterministic policy gradient (MA-DDPG) is proposed. Firstly, according to the nonlinear dynamic mechanism of the unit, multiple operating condition sub-models considering the changes of state parameters are established, and the optimal operating condition sub-model is obtained by the integral function switching mechanism. For the multi-loop complex control requirements of the coordinated control system, a multi-agent synchronous operation mechanism is proposed, and the reward function is designed with the coordinated control objectives of rapid response, stable heating and safe operation. Finally, by training the agent to interact with the environment, the multi-loop gains are continuously adjusted online to achieve multi-condition adaptive control. Simulation results show that, compared with the conventional control method, the proposed method can effectively improve the load response rate under wide range operating conditions, and ensure the stability of heating.

Under the policy of peak shaving and carbon trading, cogeneration units face a more complex background. In order to obtain the carbon emission characteristics, income distribution and carbon trading economy of the traditional extraction condensing cogeneration unit under all operating conditions, and provide a reference for the unit to deal with carbon market fluctuations when participating in carbon trading. Using EBSILON simulation software combined with python program, the carbon emission distribution and income composition of the unit under all operating conditions are obtained. The research results show that the carbon emission kilowatt hour is inversely proportional to the load. Taking 325 MW and 150 MW as examples, the carbon emission intensity of power supply increases from 903.54 g/(kW·h) to 1 015.28 g/(kW·h), and the total carbon emission is proportional to the load; The highest proportion of peak shaving income can reach 55%; The highest proportion of carbon trading income can reach 8%, and the peak shaving income accounts for a large proportion in the low load, while the carbon trading income accounts for a large proportion in the high load. Comparing the change of carbon price from 40 yuan/t to 90 yuan/t and the change of power supply carbon emission standard from 0.9 times to 1.3 times, it is found that the change of power supply carbon emission standard has a greater impact on the proportion of carbon trading income. The formulation of power supply carbon emission standard should be combined with the unit emission level. Too high or too low will affect the enthusiasm of cogeneration power plants to participate in carbon trading.

Incoloy 800H is used for high temperature section of heat transfer tubes of the first high temperature gas-cooled reactor nuclear power unit in China, of which the highest design temperature is 675 ℃. The steam oxidation properties of the Incoloy 800H at the design temperature are investigated. The structure of oxide scale of the Incoloy 800H is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The results show that, the oxidation kinetic curve of the 800H alloy in steam at 675 ℃ is close to the cubic law, namely the cubic of the weight gain is nearly proportional to the oxidation time. The oxide scale has a double-layer structure. The outer layer is mainly composed of Fe₃O₄, Fe₂O₃ and a small amount of Ni, and the inner layer is Cr₂O₃ nanocrystalline with a small amount of Ni, Al₂O₃ and TiO₂ particles distributed in it. Some internal oxide particles of Cr₂O₃, Al₂O₃ and TiO₂ are distributed in the matrix metal adjacent to the oxide layer.

By riser two-phase flow model and thermodynamic model, exergy analysis for the thermosyphon-based trilateral cycle (TTLC) proposed in the previous work by the authors is carried out to investigate the exergy performance of the system and the relevant influencing factors. The results show that, the system exergy efficiency varies in the range of 15%~30% with the increasing inlet temperature of heat source, which always helps to enhance the exergy efficiency. As the inlet temperature of cooling source decreases, the exergy efficiency changes from 23%to 27% with an optimum value. An optimization opportunity exists for the temperature difference of heater at the hot side, for example, a setting value of 4 ℃ seems to be a better choice. The riser exergy loss rate is a key factor to determine the system efficiency, especially under the condition where the temperature difference of the cycle is relatively larger. Decreasing temperature pinch point of the heater helps to decrease the internal and external exergy loss rates of the heater, but will lead to more exergy destructions in other processes. However, it exerts positive effects on system efficiency on the whole.

To study the effect of decarbonization on thermal power units, a simulation model is established to analyze the performance changes of the conventional scheme of carbon capture retrofitting in thermal power units. Moreover, a zero-output scheme of a low-pressure turbine is further proposed to improve the flexibility of the units. The conventional method uses the exhaust steam of the intermediate-pressure cylinder as the reboiler heat source, and the zero-output scheme of the low-pressure cylinder cuts off the low-pressure cylinder inlet steam. On one hand, the two methods are analyzed separately by taking a 300 MW coal-fired power unit as an example. On the other hand, the effects of the two schemes on thermal power units of the whole province is predicted by taking a province in northwest China as a research object. The results show that, the unit output range under the conventional scheme is reduced from 87~300 MW to 147~217 MW, and the power supply efficiency under rated operating conditions decreases from 37.32% to 27.02%. The minimum unit load ratio increases to about 70%. The unit load range ise widened to 47~217 MW when the zero output scheme of the low-pressure cylinder is adopted, which is 2.44 times of that of the conventional scheme. For the discussed northwestern province, the thermal power output range is reduced from 1 103~3 940 MW to 1 875~2 793 MW under the conventional scheme, and the output range is widened to 550~2 793 MW under the low-pressure cylinder zero output scheme.

The implementation of carbon pricing policy will have an important impact on the low-carbon transformation of power industry. This paper constructs a power dynamic stochastic general equilibrium (DSGE) model with carbon pricing policy, and systematically investigates the different impacts of carbon trading and carbon tax on emission reduction of the power industry under the goal of carbon emission peak and carbon neutrality. The results show that, the overall impact of carbon trading policy is greater than that of carbon tax policy, and the impact of carbon trading policy on emission reduction is achieved by inhibiting thermal power output under the carbon peak scenario, while it is achieved by encouraging green power output under the carbon neutral scenario. Different mechanism designs of carbon pricing policies, such as carbon trading and carbon tax, will have different impacts on emission reduction in the power industry under the dual carbon target. In the carbon trading policy, especially in the carbon peak scenario, there is a certain upper limit to achieve emission reduction through the market mechanism, and when the upper limit is exceeded, a "back-forcing" mechanism will be formed. In the carbon tax policy, the rebate mechanism will achieve the goal of emission reduction and the expansion of the rebate proportion will strengthen the impact on electricity emission reduction. Based on the above conclusions, relevant policy recommendations are put forward.

To realize stable combustion and refined combustion adjustment of boilers and to gain an in-depth understanding of the jet characteristics of direct flow pulverized coal burners, by taking the pulverized coal burner with surrounding air and its horizontal branch of the secondary air of a quadrangular tangentially pulverized coal boiler as research objects, the effects of throttle column height, secondary air door opening, and wind baffle angle on airflow characteristics are analyzed by numerical simulation under thermal condition. The calculation results show that, for the pulverized coal burner with a small nozzle area of the surrounding air and a thicker horizontal branch of secondary air, adding a throttle column at the position of a secondary air door can effectively improve the uniformity of velocity distribution of the nozzle area of the surrounding air. The opening degree of the secondary air door poses no noticeable effect on the airflow velocity distribution near the nozzle area of the surrounding air, and adding a wind baffle at the burner nozzle can improve the rigidity of primary air and the protection of surrounding air to primary air.