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.

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%.

Control of main steam temperature (MST) is becoming more and more challenging because of unknown disturbances caused by frequent and extensive load changes and strict control requirements for the efficiency and safety. To this end, considering the sluggish responses to the disturbances caused by high order dynamics, an anti-disturbance control scheme with stair-like dynamic matrix control (SDMC) algorithm as the core is proposed to solve fundamentally the control problem of large delay, big inertia and multiple disturbances in MST. This study aims to provide technical support for the clean and efficient use of coal and the large-scale consumption of renewable energy sources in China. A simulation example shows that the proposed improved equivalent input disturbance observer (IEIDO) can realize real-time estimation and compensation of disturbances, while SDMC can not only ensure the rapidity and stability of the steam temperature control system, but also achieve disturbance suppression according to the introduction of measured disturbance feed-forward compensation technology. Therefore, the proposed scheme can guarantee the safety, stability, economy and flexibility of the unit operation, which has a promising application future in power industry.

Measuring the investment value and investment timing accurately is crucial for coal-fired power plants' carbon capture utilization and storage (CCUS) investment. Different from the existing studies on the CCUS decision making only considering the integration mode, this study establishes the decision-making model of the CCUS investment of coal-fired power plants under the integration mode and joint venture mode from the perspective of coal-fired power plants. The decision-making model is established based on the theory of real options, considering the uncertainties of carbon price and the decreasing CCUS investment cost, and the displayed solutions of the option value and investment timing of CCUS investment in coal-fired power plants under different modes are obtained by solving the model. Based on this model, the impact of different policy incentives such as additional power quota, electricity price subsidy, investment subsidy, and carbon price volatility on CCUS investment decisions are further analyzed through numerical examples. On this basis, some policy suggestions are provided finally.

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.

In the context of Europe's vision of achieving carbon neutrality by 2050, carbon capture, utilization and storage (CCUS) technology, as an important means to achieve carbon emission reduction goals, has embraced a major development opportunity. This paper summarizes the development status of CCUS in Europe, including the financial incentive policies, carbon tax and policies, laws and regulations, and technology innovation policy for the development of CCUS technology in Europe, and the challenges in the process of developing CCUS technology in Europe, including the implementation of public funds, the comprehensive development of CCUS policies, and clear definition of responsibilities for CCUS projects. It points out that up to now, the development of CCUS technology in Europe is relatively mature. Relevant laws and regulations, financial incentives, tax support policies, and technology innovation policies have come into effect. Bioenergy with carbon capture and storage (BECCS) and direct air capture with carbon storage (DACCS) are important means to achieve negative emissions in the future. CO₂ industrial clusters and the development of transportation network can greatly reduce the transportation cost of CO₂, create profits at scale, and thus promote the application of CCUS. In 2020, China made the pledge to achieve carbon peaking by 2030 and achieve carbon neutrality by 2060. Combining the development status and relevant policies of European CCUS with basic national conditions of China, it puts forward the urgent need for current development of CCUS technology in China, and the problems that need to be solved.

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.

Chemical absorption method is an effective way to capture CO₂ from flue gas of coal burning. Compared with conventional organic amine absorbents, two-phase absorbent can significantly reduce the regenerative energy consumption and the capture cost. A new type of two-phase sorbent is developed, which uses the physical solvent diethylene glycol dimethyl ether as split-phase agent, ethanolamine and hydroxyethyl ethylenediamine as the main agent, and its absorption regeneration performance, viscosity, water phase proportion and phase separation interval is tested. Moreover, nuclear magnetic resonance (NMR) spectroscopy is carried out for the two phases in the sorbent to determine the composition and phase splitting mechanism. The organic amine composition in the formulation is optimized, and the results show that, the absorption and regeneration performance of the optimized absorbent is better than that of the conventional 5 mol/L ethanolamine absorbent. The cyclic absorption capacity can reach 2.086 mol/kg, more than 99% of CO₂ is enriched in water phase, and the flow of the absorbent entering into the regenerator can be reduced by about 40%. The viscosity of the water-rich phase is lower than 10 mPa∙s, the theoretical regeneration energy consumption is 2.688 GJ/t (calculated in CO₂), indicating the new two-phase sorbent has a good industrial application prospect.

The internal flow and temperature rise characteristics in the last stage of steam turbine low pressure cylinder under low flow rate condition is quite complex, which makes thermal power peak load regulation and cut-off transformation more challenging. By taking the low pressure cylinder of a steam turbine in a power plant as the research object, a five-stage cascade single-channel calculation model of the low pressure cylinder was established, and the working performance, flow structure and temperature rise characteristics of the low-pressure cylinder under different working conditions were numerically investigated. The research shows that, when the flow rate of the low-pressure cylinder decreases to 3.84% of the design condition, the low-pressure cylinder outputs no positive power. When the flow rate is quite low, the low pressure cylinder enters the windage condition, and the flow structures such as the hub endwall separation area, the vane separation area, the casing torus vortex, and the last stage bucket vortex appear in the last stage cascade, by concomitant of obvious windage heating effect at the tip position of rotor-stator clearance area of last stage cascade under low flow rate condition. When the flow rate decreases to 2.23% of the design condition, the average surface temperatures of the last stage vane and blade increase by 219.6 K and 243.7 K, respectively. The working performance and internal flow structure significantly change under windage condition. The temperature rise in the last stage cascade deteriorates the working environment of the blades, which needs to be taken into consideration when the steam turbine works under low flow rate condition.

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.