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  • Research & Analysis
    The Pyrolysis Characteristics of Municipal Solid Waste with Heat Transfer and Reaction Under Different High Temperature Atmospheres
    Lu Mingqiang, Yin Lijie, Yang Zhiqi, Ma Xiaobo, Chen Dezhen, Hu Song, Yu Weiwei, Zhang Ruina
    2022, 36(6): 371-376. https://doi.org/10.19806/j.cnki.fdsb.2022.06.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An experiment was conducted on the pyrolysis of municipal solid waste (MSW) in a vertical pyrolysis furnace, and the influence of following factors on the pyrolysis process was researched, such as the composition of heating gas, the preheating temperature, the heating temperature, etc. Experimental results show that, the presence of CO2 in the pyrolysis process is conducive to the pyrolysis progress, and can improve the quality of gas product and liquid product in a certain extent. The effective heat transfer coefficient increases with the increase of the preheating temperature and the heating temperature. Compared with the atmosphere of N2 and N2/CO2 at the same preheating temperature and heating temperature, the average effective heat transfer coefficient has an increase under the CO2 atmosphere. At the preheating temperature of 300 ℃ and the heating temperature of 800 ℃, the effective transfer coefficients under the three atmospheres of N2, CO2, N2/CO2 are 181.24 W/(K·m3), 244.87 W/(K·m3), 228.46 W/(K·m3), respectively. Meanwhile, the presence of CO2 promotes the heat transfer process from the heating gas to the heated MSW.
  • Research & Analysis
    Research on the Influence of BEST Regenerative System Commissioning Method on Its Operation
    Lin Yicun, Wu Gang, Zhang Mingli, Gao Jinghui, Yan Wenchen, Fu Zhilong, Lü Jiming, Deng Shunhuai
    2022, 36(6): 377-381,386. https://doi.org/10.19806/j.cnki.fdsb.2022.06.002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The two commissioning methods of the back pressure extraction steam turbine (BEST) regenerative system were introduced in detail, and the influence of the commissioning method on main parameters was analyzed. Results show that, the lower back pressure of the BEST and the over-limited power of the generator unit are caused by the adoption of the random commissioning of heaters. The method of commissioning the low pressure heater at first and then commissioning the high pressure heater needs a longer time, while this method is conducive to the establishment of the back pressure of the BEST. In this way, the phenomenon of the over-limited power of the generator unit caused by the lower back pressure of the BEST can be avoided. This may reduce the coal consumption of the unit and improve the economy of the unit.
  • Research & Analysis
    Experimental Research on the Ash Deposition Characteristics of Ammonium Bisulfate in Air Preheater
    Shan Xinchen, Lei Jiankang, Zhao Lingling
    2022, 36(6): 382-386. https://doi.org/10.19806/j.cnki.fdsb.2022.06.003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the ash deposition characteristics of ammonium bisulfate (ABS) on the surface of air preheater regenerative plate, an air preheater simulation test bench was independently designed and built.The effects of temperature, gas flow rate, mass ratio of ABS to fly ash and ash particle size on ash deposition characteristics were studied. Results show that temperature is an important factor in the ABS blockage of air preheater regenerative plate. The ABS adhesion ratios of plate A and B were 31.7% and 27.9% respectively when the temperature was 493 K. The growth rates of ABS adhesion ratios of these two kinds of plates both increased when the gas flow rate declined. The ABS adhesion ratio on the surface of plate A was slightly higher than that of plate B with the same gas flow rate. The ABS dust accumulation on the surfaces of regenerative plates significantly reduced when the mass ratio of ABS to fly ash declined. The ABS adhesion ratio of fly ash particles with larger particle size is smaller.
  • Research & Analysis
    Diagnosis and Analysis of the Fouling on Flow Path of Steam Turbine in a Heat and Power Cogeneration Unit
    Liu Chuanliang, Hao Ning
    2022, 36(6): 387-392. https://doi.org/10.19806/j.cnki.fdsb.2022.06.004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For the problem of the increased axial thrust force of a 57 MW extraction steam-condensing steam turbine in a heat and power cogeneration unit, analyses were conducted on corresponding parameters of the flow path, and an evaluation method was established for the flow capacity coefficient of the stage group in the steam turbine. Results show that, with an increase of the operation time, the flow capacity of the stage group decreases gradually. The fouling and blocking occurs in the flow path, while the blocking is aggravated by an increase of the operation time. The fouling is mainly distributed in the No.3- No.6 high-middle pressure stages, and the distribution of the fouling is in accordance with the result of the flow capacity coefficient. The flow path covered by the large amount of sodium silicate is caused by the severe content over-limitation of the silicon dioxide in demineralized water.
    • Material Technology
  • Material Technology
    Fracture Analysis on Dissimilar Steel Weld of the Low Temperature Reheater Tube in a Boiler
    Niu Yujing, Hu Fengtao
    2022, 36(6): 393-396. https://doi.org/10.19806/j.cnki.fdsb.2022.06.005
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    Analyses were conducted on the reason of the weld cracking of the low temperature reheater tube in a power plant boiler. Results show that the welding quality of the dissimilar steel weld between the low temperature reheater and the pull plate is not good, and the welding of the pull plates can not meet the design requirements, which result in the high stress in the low temperature reheater. The micro-cracks gradually expand into the macro-cracks during the boiler operation and finally lead to the leakage.
    • Environmental Technology
  • Environmental Technology
    Research on the Performance of Mercury Removal Adsorbents in Flue Gas by Thermal Regeneration
    Wu Linhu, Wu Jingmao, Wang Hui
    2022, 36(6): 397-401. https://doi.org/10.19806/j.cnki.fdsb.2022.06.006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The commonly used adsorbents for thermal regeneration of mercury removal from coal-fired flue gas were summarized, including sulfur modified adsorbent, metal oxide modified adsorbent, and magnetic adsorbent. The performance of adsorbents with thermal regeneration was analyzed, and the influencing factors of thermal regeneration were explored. This may serve as a reference for the improvement of the mercury removal efficiency of adsorbents with thermal regeneration in coal-fired power plants.
  • Environmental Technology
    Feasibility Research on the High Concentration Recirculation Cooling Water with Green Phosphate-free Solution in a Power Plant
    Wu Hongliang, Liu Caixiu, Lü Haojun, Yu Yukun, Zhang Juan, Peng Longfei, Liu Weijian
    2022, 36(6): 402-405. https://doi.org/10.19806/j.cnki.fdsb.2022.06.007
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    For the recirculation cooling water system with the green phosphate-free solution in a power plant, an introduction was made on the performance of the phosphate-free scale inhibitor and the phosphate-free corrosion inhibitor, and corresponding green phosphate-free solutions were selected for the recirculation cooling water with the 10 times concentration by simulation and calculation. After which, the performance of corrosion inhibition and scale inhibition was verified. Results show that, the performance of corrosion inhibition and scale inhibition can satisfy the requirements, and the recirculation cooling water system with the selected green phosphate-free solution in the power plant can operate efficiently and stably under the condition of the 8-10 times concentration of the recirculation cooling water.
    • Automatic Control
  • Automatic Control
    Fault Ddetection and Diagnosis of Multimode Thermal Processes Based on GSA-RGMM
    Pu Jianfei, Ren Shaojun, Zhou Dongyang, Cao Jun, Fan Wei, Si Fengqi
    2022, 36(6): 406-413. https://doi.org/10.19806/j.cnki.fdsb.2022.06.008
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Robust Gaussian mixture model(RGMM) algorithm was introduced to establish fault monitoring model to solve the problem that traditional Gaussian mixture model(GMM) algorithm was sensitive to initial parameters, and a fault isolation method based on gravitational search algorithm(GSA) reconstruction was proposed to locate fault variables accurately in multimode thermal process. A multimode thermal process fault monitoring model was established through the RGMM algorithm, the optimal Gaussian component and statistical distribution parameters of the model were iteratively solved by the expectation maximization (EM) algorithm. When the monitoring indexes exceeded the limit, the GSA reconstruction method integrating with monitoring indexes was adopted to locate the fault variables and fault amplitude. The algorithm was evaluated using a multimode numerical example and a high-pressure heater example. The results show that the GSA-RGMM algorithm has a high fault detection rate in the multimode thermal process fault monitoring, can better locate the fault variables with high fault diagnosis rate and low misdiagnosis rate when the faults is detected, and is suitable for real-time fault monitoring and diagnosis of multimode thermal processes.
  • Automatic Control
    Fault Diagnosis Method of Power Plant Equipment Based on PCA-ILARS-DNN Case-based Reasoning Model
    Xu Tianhong, Wang Peng, Wang Yong, Chen Rongze, Si Fengqi
    2022, 36(6): 414-420. https://doi.org/10.19806/j.cnki.fdsb.2022.06.009
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A method establishing power plant equipment fault diagnosis model based on case-based reasoning from historical database system was proposed for insufficient ability to extract fault information and low diagnostic rate. Principal component analysis (PCA)-improved least angle regression (ILARS) case representation method was used to extract the fault information of power station equipment into a unified form of data cases, so as to construct the typical fault case database of power station equipment. On the basis of the existing case database, deep neural network (DNN) algorithm was used to carry out case retrieval and fault diagnosis. Through the diagnosis effect, the influence of PCA-ILARS algorithm was compared with other case representation methods on fault diagnosis rate. The result of engineering application shows that the proposed PCA-ILARS-DNN algorithm is superior to other conventional case representation methods, and has a higher identification rate for power station equipment fault diagnosis equipment.
  • Automatic Control
    Optimization of the Coordinated Control System in a 660 MW Ultra Supercritical Unit
    Ge Jusheng, Liu Xiao, Wang Zhaoshun, Gu Wei, Liu Zhou
    2022, 36(6): 421-426. https://doi.org/10.19806/j.cnki.fdsb.2022.06.010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For a 660 MW ultra supercritical unit in a thermal power, the large fluctuation of following key parameters had an influence on the unit when the existing coordinated control system in operation, such as the main steam pressure, the main steam temperature, the furnace pressure, etc. To solve the problem, a comprehensive optimization was conducted on the key loops of the unit, including the auto generation control (AGC), the primary frequency control, the boiler master control, the turbine master control, the adaptive variable load feedforward, the fuel control, the air and flue gas control, and the steam temperature control, while the AGC of the unit was put into operation after the optimization. Actual operation data show that the optimized coordinated control system has the advantages of the fast regulation response speed, the small load dynamic deviation, the small fluctuation of the main steam pressure, the main steam temperature, the furnace pressure and other key parameters, which can satisfy the safety and stability of the unit operation.
    • Operation & Retrofit
  • Operation & Retrofit
    Retrofit on Comprehensive Recovery of Exhausting Medium and Waste Heat of a Supercritical Once-through Boiler Without Boiler Water Circulating Pump
    Liu Guibing, Ji Yong, Yang Guangjun, Shi Fangcheng, Sun Qi, Zhang Liqian, Wu Guodong
    2022, 36(6): 427-432. https://doi.org/10.19806/j.cnki.fdsb.2022.06.011
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To realize the comprehensive recovery of the exhausting medium and waste heat of the supercritical once-through boiler during the start-up and normal operation stage, retrofits were conducted on following systems in a 600 MW unit, such as the boiler start-up system, the drainage of soot blowing system, the primary-secondary air heater system, the regenerative feed-water heating system, etc., while the start-up mode of the unit was optimized. Results show that, by adopting the recovery retrofit, the start-up operation is improved with a lower consumption of the fuel and the steam from the adjacent boiler during start-up, and a shorter start-up time, which can provide the advantage to the full-load denitration of the boiler and realize the comprehensive recovery of the exhausting medium and waste heat. This retrofit presents a good economy.
  • Operation & Retrofit
    Comparison and Analysis on Wide-load Denitration Retrofit Schemes for an Ultra-supercritical Boiler
    Xu Min
    2022, 36(6): 433-436. https://doi.org/10.19806/j.cnki.fdsb.2022.06.012
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For the wide-load denitration in an ultra-supercritical boiler, a comprehensive comparison and analysis was conducted on following technical retrofit schemes, such as the economizer grading, the flow displacement of economizer, the bypass of flue gas, etc. Calculation results show that the technical retrofit scheme with the bypass of flue gas in the unit has a good feasibility. By extracting the high temperature flue gas at the inlet of the horizontal low temperature reheater, the flue gas temperature at the inlet of the selective catalytic reduction (SCR) denitration system could be improved, and which could be maintained above 300 ℃. This may satisfy the requirements of the denitration operation of the unit under 30% boiler maximum continuous rating (BMCR) load, and realize the wide-load denitration.
  • Operation & Retrofit
    Retrofit of the Cooling Air Source System for Flame Detection in a 1 000 MW Boiler
    Xu Yuwei
    2022, 36(6): 437-440. https://doi.org/10.19806/j.cnki.fdsb.2022.06.013
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For a 1 000 MW boiler in a power plant, the coking and burning damage of the flame detector probe occurs easily during high temperature operation, which is caused by the small flow rate of the cooling air for flame detection. To solve this problem, the cooling air form the existing air source system for flame detection was replaced by from the main piping of the cooling primary air source, while the existing fans of the cooling air for the flame detection shut down for standby. The retrofitted system can ensure the normal operation of the boiler and save the cost.
  • Operation & Retrofit
    Analysis of Flue Vibration of Low Temperature Economizer and Damping Measures
    Gong Jun, Li Kai, Zhang Pingheng, Sun Jian, Jin Jianrong, Zhang Hong, Tan Qun, Zhou Yimin
    2022, 36(6): 441-444. https://doi.org/10.19806/j.cnki.fdsb.2022.06.014
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Because the actual flue gas flow rate far exceeds the design value, the Karman vortex frequency falls into the acoustic resonance frequency range, resulting in large vibration of low temperature economizer flue. Results show that the lower limit of acoustic resonant frequency range increased with the increase of the number of anti-vibration baffles, so as to avoid the close Karman vortex frequency. The inhomogeneity of the flow field resulted in local fluid elastic excitation and wide frequency resonance of Karman vortex. The flow field uniformity coefficient decreased from above 0.55 to 0.28 after the diversion grid was installed, and the flow field uniformity was improved. By reducing the spacing of ribs, increasing the anti-vibration baffles, adjusting the fulcrum of equipment and installing the guide grid, the abnormal vibration of low temperature economizer flue could be completely eliminated.