Advanced Materials Research Vols. 732-733

Abstract: To provide a theoretical guidance for the application of selective non-catalytic reduction (SNCR) in a large capacity utility boiler, numerical study of SNCR process in a 600 MW utility boiler was performed based on computational fluid dynamics (CFD) code Fluent. Good agreement of the calculation results with the industrial test data confirms the reliability of the calculation model. It is found that the NO removal efficiency is low and NH₃-slip is high, because the injected reducing agent could not mix with the flue gas adequately, and the furnace temperature is not uniform in utility boiler with large furnace size. Aiming at this problem, the commissioning scheme for reducing agent injection system was optimized, and CO was added together with the reducing agent. As a result, NO removal efficiency increases from 19% to 27%, and NH₃-slip decreases from 59 ppm to 13 ppm.

Abstract: The ANSYS-ICEPAK is used to establish and analyze the thermal condition of the cooling modular of the looped pulsating heat pipe in the street light, the reliability is proved by experimental results of thermal analysis. The experimental results show that: the temperature distributions on the surface of the lamp shell and loop heat pipe are uniform, and the average temperatures of them are about 40°Cand 43°C; while the maximum temperature of the chip base reaches 67.5°C. Through comparison, the simulation results are close to the actual measured results.

Abstract: In order to improve the performance of aero engines, trying to increase the turbine inlet temperature is an important way. But the turbine inlet temperature of modern aero engines can be more than 2000 K, which is far more than what the materials can bear. So advanced cooling technologies should be introduced to solve this problem. Using the conjugate heat transfer method, this paper researched the aerodynamic characteristics of a certain turbine blade with complex cooling structures. Some conclusions can be drawn: the velocity of the air flow and different distributions of coolant flow for turbine blade with multiple cooling air inlets have great influence on the cooling effect; the cooling effect decreases as the temperature ratio decreases; with the same mass cold gas, the less film cooling holes, the worse cooling effect; therefore, a reasonable air flow distribution plays an important role in obtaining good cooling effect.

Abstract: It is important for conventional thermal power units to participate in frequency adjustment and peak regulation for the safe operation of grid side. This paper research on coordinated control system (CCS) for boiler-turbine units based on fractional-order control (FOC). The realization of fractional-order PID (FOPID) controller in distributed control system (DCS) is provided. The engineering application results show that this algorithm is easy to be realized in project by applying all sorts of existing algorithms in DCS. Furthermore, this algorithm can overcome the large lag and inertia for boiler and improve the primary frequency and automatic generation control (AGC) tracking performance in boiler-turbine CCS effectively.

Abstract: The main steam temperature process has the characteristics of large inertia, large time delay and time-variation , to solve this problem, the fuzzy PID cascade control system with Smith predictor is presented .The improved Smith predictor with the effect of filtering was used in the main loop of the cascade control system, and fuzzy PID compound controller was used as the main controller based on the advantage of fuzzy control and PID. Through establishing the mathematical model and simulating the main steam temperature control system, either the parameter changed or invariable, the results show that the method can improve the control qualities and enhance the robustness and stability of the control system.

Abstract: The ash deposition and the gas velocity affect the exhaust gas temperature of a CFB boiler. The surface contamination in a CFB boiler is quite different from that one in the pulverized coal boiler. It is suggested that the surface contamination in a CFB boiler should be determined according to the ash content in the fuel as well as the cyclone collection efficiency. The effect of the gas velocity on the surface contamination is very important. The lower gas velocity causes more serious contamination, leading to the higher exhaust gas temperature. The staged tube arrangement should be employed. And the gas velocity should be designed higher to enhance the self-cleaning ability. Anyway, the soot blower should be designed in the CFB boiler convective heating surface. The ratio of the practical contamination coefficient to the design one, k, is the strong function of gas velocity, w_y, which was expressed as: k=1+exp(6.8-w_y)

Abstract: There is a contradiction in selecting the running temperature for CFB boilers burning Fujian anthracite, in order to simultaneously satisfy the requirement of efficient combustion and high desulfurization efficiency. Based on numerical simulation and industrial experiments, the effect of the running temperature on the carbon content in fly ash and the desulfurization efficiency were analyzed for two types of CFB boilers with different capacities. It is found that, with the rise of running temperature, both decrease quasi-linearly. For the 75 t/h CFB boiler, when the running temperature is lower than 950 °C, the carbon content in fly ash is very high, causing a low burnout efficiency; maintaining the running temperature at 1000 °C is favorable for the fine char to be burned out, however, continuous raise becomes almost useless. For 440 t/h CFB boiler, a higher burnout rate of the fine char particles can be obtained when the running temperature is kept at about 950 °C, and further increase brings no evident benefit either. For the 75 t/h and 440 t/h CFB boilers burning Fujian anthracite, considering both the boiler efficiency and the combustion desulfurization efficiency, the optimal running temperature should be respectively about 980 °C and 950 °C.

Abstract: Heat exchanger is an equipment for general purpose. It is very popular in the industry of energy and power, refrigetion,chemical and oil. And it is also very important for company, energy and application. Its efficiency of transferring heat and its safety of operation are very important for our society, especially in these days energy becomes more and more valuable. In this paper ，we used practical examples to describe the calculation of heat transfer of surface type heat exchanger .

Abstract: The design optimization of steam turbine cold end is an important measure to ensuring safety and economic operation of the unit. Based on the universal calculation method of steam turbine output correction, considering investment cost, operation cost, cooling water expenditure and hot pollution cost, the design optimization of steam turbine cold end was carried out. An example of the domestic 300MW unit was presented to show the validity of this method. The design optimization results can be used as a foundation for the equipment selection and inviting bid documents compilation of steam turbine cold end in coal-fired power plant.

Abstract: A novel photovoltaic /thermal (PV/T) module is invented, which use micro heat pipe array (MHPA), a flat heat pipe, to cool the solar cell. The PV/T module can achieve the purpose of cogeneration by collecting and utilizing waste heat while cooling the solar cell and improving power efficiency. In order to test the performance of PV/T module based on MHPA, instantaneous thermal efficiency test was performed. The intercept of measured instantaneous thermal efficiency curve can reach 41.4%, the slope is 3.95. The temperature of PV module is the key factor of the influencing electric efficiency. The PV/T modules electric efficiency is kept between 10.5% and 12.3% during the test. Solar energy utilization total efficiency at 20°C inlet temperature can reach more than 50%, and comprehensive performance efficiency can reach above 70%.