Table of Content

05 December 2018, Volume 51 Issue 12

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Analysis on Peak Load Regulation of E-stage Combined Cycle Heating Unit

ZHANG Li, ZHANG Ziyu, KONG Xiangcan, YAO Hao, GU Qingfeng, YU Yue, ZHOU Weiwei, QIAN Jiangbo, KONG Xiaoye

2018, 51(12):  1-6,28.  DOI: 10.11930/j.issn.1004-9649.201708122

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Taking the PG9171E gas turbine as the top cycle unit as the research object, the gas-steam combined cycle system model for varying operation conditions is established by using the EBSILON software. The influence of the extraction rate variation on the peak-shaving capacity of the combined cycle is analyzed by changing the steam extraction and boundary conditions. The results show that the peak regulation margin of the unit is 32.16~213.65 MW when the steam extraction is lower than 135t/h. The minimum and maximum generation power of the combined cycle unit with different extraction capacity are compared in this paper. It is found that the minimum generation power increases and the maximum generation power decreases with the increase of the extraction capacity. The results can provide an important reference for the economic operation of combined cycle units and the decision of power grid peak-shaving.

Numerical Simulation Study of Film Cooling Effectiveness on the Rotating Gas-Turbine Blade

LI Luping, TANG Xuezhi, ZHANG Hao, HUANG Zhangjun

2018, 51(12):  7-13,35.  DOI: 10.11930/j.issn.1004-9649.201805104

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In this paper, the film cooling effectiveness of rotating gas turbine blade is investigated through numerical simulations. The cooling characteristics under different blowing ratios in rotating state as well as static state are compared in details. The average film cooling efficiency and cooling non-uniformity coefficient are used to evaluate the film cooling effect. The results show that on the pressure surface of the blade, due to the blade rotation the momentum of the jet cooling air in the normal direction will increase after the airflow passes through the film hole and then intensify with the mix of mainstream, such that the film cooling efficiency on pressure surface is lower than that of the static state. While on suction surface the rotation will result in the decrease of the normal momentum of jet air through the film hole, which will make it remain well attached to the surface and move downstream. Therefore the film cooling efficiency on suction surface is higher than that of the static state, and the average film cooling efficiency on the trailing edge is significantly boosted in comparison with the static state. The cooling non-uniformity coefficient on rotating blade is slightly greater than that of the static blade.

Investigation on Premixed Combustion Characteristics with Radial-Swirled Flow in High Pressure Combustion Chamber

FU Zhongguang, WANG Shucheng, SONG Yilin, ZHANG Gaoqiang, GAO Yucai

2018, 51(12):  14-19.  DOI: 10.11930/j.issn.1004-9649.201810002

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The combustion characteristics of a dry low emission high pressure combustion chamber are studied through numerical simulation. Then the model is validated by comparing the simulation result with the experimental data in the literatures. The velocity field, pressure field and temperature distribution at the exit of the combustion chamber under different inlet Reynolds number are analyzed. It is shown from the results that the value of Reynolds number has great impact on the flow field in the combustion chamber. As the Reynolds number increases, the central recirculation zone tends to expand with higher axial velocity at the central recirculation zone. In addition, the temperature at the exit of the combustion chamber rises, where the cross section temperature gradually increases from the external to the center. Besides, as the flow distance increases, the maximum velocity and range of the recirculation zone tend to decrease with the intensity of the reflux lessened and shrinking area of the external recirculation zone.

Research on the Temperature Control Optimization Method to Reduce Gas Consumption of Gas Turbine

FAN Jinji, ZHANG Chi

2018, 51(12):  20-28.  DOI: 10.11930/j.issn.1004-9649.201803097

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The exhaust gas temperature of the gas turbine affects the efficiency of gas-steam combined cycle plant. The effective control of the exhaust gas temperature depends on the temperature control strategy of the gas turbine. This paper introduces the design principle and control method of temperature control for GE gas turbine. Regarding the calculation process of different types of temperature control curves, corresponding optimization methods are analyzed and explored. Based on the exhaust temperature and economic requirements, and then combined with the performance of existing equipment, the IGV temperature control line (TTRXGV), pressure ratio temperature control line (TTRXP), and power temperature control line (TTRXS) are optimized for temperature control strategies. After the optimization, the gas consumption of gas turbine is reduced by 0.000 5 m³/kWh after being converted into pure condensing condition. The economy is improved under the condition that the requirements are satisfied for secure and stable operation of the gas turbine, which demonstrate the effectiveness and reliability of the optimization method.

Study on the Mechanism of Wet-clogging Issue in Gas Turbine Inlet Air System and Correction Schemes

ZHANG Tao, LIU Zhitan, FU Zhongguang, HAO Hongliang, ZHU Hongfei, YAN Zhiyuan

2018, 51(12):  29-35.  DOI: 10.11930/j.issn.1004-9649.201809095

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When gas turbines are operated under high humidity environments, the air intake filtration systems may experience rapid increase of resistance, which can seriously affect the security and economy of gas turbine operations, i.e. "wet-clogging". Based on the studies on the real case, the internal mechanisms of wet-clogging have been analyzed thoroughly in the paper. Furthermore, a passive preventive scheme by improving the water mist endurance and an active preventive scheme by adjusting the relative humidity and temperature of the inlet air were put forward respectively. According to the results from water mist endurance testing and compressor inlet bleeds heating (IBH), both approaches mentioned above are capable of resolving the issue of wet-clogging effectively.

Research on the Impacts of Gas-steam Combined Cycle Air-inlet Cooling System on Unit Performance

ZHANG Gaoqiang, FU Zhongguang, WANG Shucheng, ZHANG Tianqing

2018, 51(12):  36-41.  DOI: 10.11930/j.issn.1004-9649.201809102

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Taking PG9171E gas-steam combined cycle power plant as the research object, in this paper the combined cycle and intake cooling systems were modelled. The performance changes of the gas turbine side, the heat recovery steam generator side and the steam turbine side of the unit with the inlet cooling system were then analyzed. The results showed that for every 10 degrees of the temperature rise, the output of the E-type combined cycle unit with the intake cooling system will increase by about 9% while the efficiency of the heat recovery steam generator is reduced by 3%. In addition, by properly tuning steam parameters and taking full advantage of the waste heat resources the steam turbine will generate more output by about 2.1MW and the combined cycle efficiency can be improved by about 0.3%.

Research on Model Predictive Control for MMC-HVDC with Low Switching Frequency

ZHANG Kaiyu, FENG Yuyao, CUI Yong, YANG Xingwu

2018, 51(12):  42-47,131.  DOI: 10.11930/j.issn.1004-9649.201711152

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Being simple in principle and capable of controlling multiple objectives, the model predictive control (MPC) is more and more widely used in modular multilevel converter (MMC). However, the traditional MPC strategy has the problems of large computation and high switching frequency. An improved MPC method is thus proposed in this paper. Firstly, the current cost function is used to find the optimal combination of switch states; and then, the combination of switch states is optimized according to the input modular number on each sub-bridge arm at the adjacent time; finally, an integrated cost function is designed to control the capacitor voltage balance and eliminate the circulating current. The proposed method not only substantially reduces the calculation burden, but also reduces the average switching frequency of MMC and the power system's energy consumption, and is thus applicable to MMC system. An 11-level three-phase MMC-HVDC simulation system is established based on Matlab, and the simulation results have verified the effectiveness and feasibility of the proposed method.

Relationship between the Power Loss of Modular Multilevel Converter and Transmission Voltage Level

RONG Fei, WANG Yazhou, RAO Hong, ZHOU Baorong, LI Hongxin, LI Wenjun

2018, 51(12):  48-55.  DOI: 10.11930/j.issn.1004-9649.201706130

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Normally MMC (modular multi-level converter) is adopted in the flexible HVDC transmission system. The power loss of converter is one of the most important indexes to evaluate the performance of flexible HVDC system. In this paper, an analytical expression for the on-state and switching loss of MMC is derived. As can be seen from the expression, the power loss of converter is not only related to the number of MMC sub modules, but also the capacity and voltage level of the flexible HVDC transmission system. In this paper, a detailed investigation of the influence of the capacity and voltage level of HVDC system on the power loss of converter is carried out, so as to identify the optimal voltage class that reduces the power loss to a minimum. Simulation results show that the proposed method can be used to find out the voltage level that helps lower the power loss.

Research and Application of External Network Equivalent Method in Short Circuit Current Calculation

YANG Jingang, HE Chengming, LI Shunxin, SHI Zhiping, LI Xiaorong, SHI Shaowei

2018, 51(12):  56-62.  DOI: 10.11930/j.issn.1004-9649.201711078

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The time consuming of short circuit current calculation increases with the development of the power grid scale, and the requirement for computation software is enhanced. An external equivalent method is introduced for calculation of the short circuit current in order to improve the calculation efficiency. Firstly, the node admittance matrix of the whole power network is equivalently simplified to form the additional elements of the boundary region. And then a simplified power network composed of the study region and boundary region is constructed to calculate the short circuit current in the study region. The validity and efficiency of this proposed algorithm is theoretically analyzed and verified on the IEEE 39-node power system. Finally, the North China power grid is used as an example for external equivalent simplification to form the short circuit calculation data of a certain area, which greatly reduces the scale of the power system and improves the calculation efficiency of short circuit current.

Fault Location for Low Voltage Active Distribution Network Based on Perturbation Method

ZHANG Pan, ZHANG Yu, DING Yi, LI Wuxing, JIANG Huilan, CHEN Juan

2018, 51(12):  63-71.  DOI: 10.11930/j.issn.1004-9649.201803206

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With the access of distributed generation to low-voltage distribution network, the power flow of the distribution network becomes more complicated. As a result, the traditional fault location scheme based on one-way power flow no longer applies. This paper proposes a perturbation based phase-mode transformation to achieve the fault location for low-voltage distribution networks with distributed generation. Against the asymmetry of three-phase line parameters in low-voltage distribution network, the line parameter impedance matrix perturbation is constructed with the perturbation theory to derive the phase mode transformation matrix which can decouple the original three-phase networks into three mutually independent sequence graphs, consequently realizing the decoupling of the parameter impedance matrix of asymmetric lines. And then, A criterion is derived for judging the fault section of the low-voltage active distribution network according to the changes of the fault component phase angle differences of the section phase-mode transformation current before and after the fault, realizing the accurate position of the low voltage distribution network. The Matlab/Simulink simulation results show that the proposed method can quickly and accurately locate the fault section and solves the influence of the asymmetry of distribution network parameters on positioning accuracy.

Grounding Fault Analysis and Protection Scheme Study for Composite Grounding Arc-suppression Mode

YU Bin, YIN Xianggen, ZHU Weijun, WU Xiaozhong, NING Chunhai, LI Hui, GONG Hanyang, XU Hao, LIU Haifeng

2018, 51(12):  72-79.  DOI: 10.11930/j.issn.1004-9649.201803018

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The wiring form of typical grounding mode and composite grounding arc-suppression mode of distribution network neutral point are discussed. Centering on analysis of single-phase ground fault, and based on a wide-range survey of typical structure and accessing equipment of 10 kV distribution network, accurate simulation model reflecting engineering practice is established according to the existing power design standards. This paper not only describes the principle of grounding fault transfer mode and intelligent multimode grounding mode respectively, but also analyzes their fault treatment process by simulation. In addition, a line selection method based on the first transient half wave of fault grounding and operation grounding of the own line is put forward for grounding fault transfer mode, and the effect of transition resistance on zero-sequence current protection for intelligent multimode grounding mode is analyzed. This research lays a solid theoretical foundation for the engineering application of composite grounding arc-suppression mode.

Wide-Area Damping Control of Power System Based on a ε-Tradeoff “Damping-Time Delay” Method

YU Miao, LU Haoyang

2018, 51(12):  80-87.  DOI: 10.11930/j.issn.1004-9649.201802038

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There exists time delay problem in solving the inter-area low-frequency oscillation of power system, which brings significant influence on the system stability. In order to solve this problem, a reduced-order mathematical model of power system is firstly established. And then a tradeoff-based idea is proposed to achieve wide-area damping control. Based on the linear matrix inequality (LMI) toolbox, the Lyapunov time-delay stability criterion is used to acquire the wide-area damping controller (WADC) parameters. And then the system stability is proved by using an indirect method of time-delay segmentation, and the damping characteristics of the power system is analyzed. Finally, simulations are carried out by using the four-machine two-area model. The simulation results show that the rotor angle and reactive power tend basically stable in about 6 seconds, and the damping stability of power system is improved effectively compared with other conventional WADC methods.

Research on A Fault Sensing and Analysis Supporting Platform for Power Grid

QIE Zhaohui, CUI Xiaodan, LI Wei, LIU Fusuo

2018, 51(12):  88-94.  DOI: 10.11930/j.issn.1004-9649.201801118

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In order to improve the sensing and fault analysis ability of the power grid, a novel panoramic recording platform is developed in this paper. The data requirement for fault analysis is proposed according to the reformation of fault forms under the rapid development of UHV AC and DC power grid. The requirements for panoramic recording platform architecture and communication are also presented. Simulation results show the developed novel recording platform have good data recording performance and can guarantee the complete collection of fault data, which could realize the whole grid fault data integration.

Comparative Analysis on PA and UT Technologies in Defect Detection Rete of Gas-insulated Enclosed Electrical Equipment Enclosure

QIAO Yaxia, LUO Hongjian, ZHANG Pengfei, ZHANG Hao

2018, 51(12):  95-100.  DOI: 10.11930/j.issn.1004-9649.201804074

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Based on the test and simulation analysis of aluminum shell defect specimens, three methods of phased array inspection (PA), conventional ray test (RT) and conventional ultrasonic testing (UT) for welding seam detection of aluminum shell of the gas-insulated transmission lines were studied and compared. The test results show that the detection rate of UT and PA is superior to that of RT for face-type defects with greater hazards.Phased array detection (PA) is easier to detect the best angle of defects, has a higher detection rate for hazardous defects. Moreover, PA can obtain more information of defect feature. The test results provide a basis for the non-destructive testing process of gas insulated transmission line (GIL) shell in Sutong pipeline corridor project.

Study on Factors Affecting Validity of Field Calibration of GIS UHF Sensors

GONG Yanpeng, PENG Jiang, BI Jiangang, YANG Ning, YAN Chunyu, CHANG Wenzhi, XU Yuan, TAO Shiyang

2018, 51(12):  101-106,113.  DOI: 10.11930/j.issn.1004-9649.201708034

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In this paper, the factors affecting the on-site calibration of GIS UHF sensors (ultra-high frequency sensors) are studied and compared. The characteristics of propagation and attenuation of UHF signals excited by different typical flaws and steep pulse sources are compared and analyzed on the real test platform of GIS. Then, the wavelet packet analysis is used to analyze the propagation rules of signals in different frequency. Finally, combined with the status of ultra high frequency sensors of GIS on site, the validity of the experiment is tested, and some problems are found to be defective.

Susceptibility of Suspended Insulators in Xuzhou Cement Contaminated Area

BAI Lu, GAO Song, WEN Taoyuan, YANG Linjun

2018, 51(12):  107-113.  DOI: 10.11930/j.issn.1004-9649.201708177

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In the case of natural fouling of insulators, the salt ash, the particle size, the surface elemental composition, and the particle morphology of the upper and lower surfaces would change during the process of surface contamination. In this paper, the insulator string of overhead transmission lines in Xuzhou, Jiangsu Province is taken as an object to test and analyze the physical and chemical characteristics of the surface contamination of suspension insulator insulators. Meanwhile, the surface contamination characteristics of insulator in Xuzhou area are discussed. The key findings are as follows:the insulator equivalent salt deposit density and non-soluble deposit density are related to weather, and the dirt accumulation achieves maximum value in February, which has a great relationship with the main surrounding pollution sources. In the cement polluted area, Xuzhou, the filthy degree on the upper-surface is larger, the filthy degree on under-surface is relatively smaller; The particle size, composition and content of the fouling on the surface of insulator differ greatly under different environments.. Conclusion can be used as reference basis of insulators' operation and maintenance in cement polluted area.

Research on and Application of Tertiary Air External Separation Technology in Low Nitrogen Combustion Retrofit

DU Junwen, SHEN Ming, LI Sheng

2018, 51(12):  114-117.  DOI: 10.11930/j.issn.1004-9649.201806015

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Regarding the problem of high NO_x concentrations in a 330 MW boiler with quadrangular circular firing and hot air coal-powder feeding, based on the analysis of the impacts of tertiary air on NO_x generation, the key components of the combustion system are optimized. To be more specific, the low level nitrogen burner with horizontal primary air separation, plus the tertiary air with external separation together with the in-depth air classification technologies are implemented in the entire retrofit scheme. Especially for the tertiary air that may highly affect the NO_x generation, the external separation and vertical space classification and delivery technologies are used. It is evident from the actual operation that after the retrofit, the NO_x generation volume is reduced significantly, while the boiler combustion and operation still remain stable state without any side effect on the boiler efficiency.

Study on the Main Steam Temperature Control System Based on Fuzzy Adaptive Internal Model Control

GUO Ruijun, ZHANG Guobin, JI Yu, LI Xu, DU Ronghua, ZHOU Lei, DANG Shaojia

2018, 51(12):  118-123.  DOI: 10.11930/j.issn.1004-9649.201806158

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In this paper, the first order lag model is used as the generalized object model of main steam temperature to design the fuzzy adaptive internal model control based main steam temperature control system. The parameters of the object model are identified under different operation conditions. According to the model parameters and fuzzy adaptive rules, the controller parameters are adjusted automatically. The designed system is simulated and applied in a power plant as well. The results show that, compared with the conventional cascade PID controller and the Smith prediction control, the system has a better control quality when the system operates under load disturbances or with model parameter deviations as well as under different operation conditions.

Application of Data Reconciliation in Steam Turbine Performance Monitoring

HU Jiangen, GU Zhenghao, BAO Jinsong, ZHU Meifang, ZHANG Bao

2018, 51(12):  124-131.  DOI: 10.11930/j.issn.1004-9649.201805001

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In the steam turbine thermodynamic cycle, the measuring system has provided redundant measuring points. Generally, the main water flow, the main condensate flow and the feed water pump inlet flow are chosen as the mainstream in the on-site performance calculation. In this paper, by using the data reconciliation method, the redundant flow measurement point information is taken to perform data reconciliation calculation regarding the performance data of a real power plant. Then the uncertainty changes of the calculation result are analyzed. The result shows that the data reconciliation can effectively reduce the uncertainty of the calculation result.

Statistics and Analysis of the Thermal Control System Faults in the Power Plants Nationwide Throughout 2017

XIA Kechao, TENG Weiming, YIN Feng

2018, 51(12):  132-138.  DOI: 10.11930/j.issn.1004-9649.201806164

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In this paper, 148 typical cases involving system design, configuration, installation, maintenance and operation are selected and categorized from the collection of the thermal control system faults that occurred in the power plants nationwide throughout 2017. Through the statistical analysis of these typical cases, regarding the problems including the aging of the control system and auxiliary equipments, inadequate testing and maintenance of the automatic system, high failure rate of the on-site standalone control devices and repetitive occurrence of the typical faults, etc., the relevant pre-control measures and suggestions to further eliminate the potential risks and improve the system reliabilities are proposed such as equipment degradation analysis and upgrading, automatic system quality maintenance, specification normalization and implementation, and strengthening the effectiveness of the technical management and the personnel training.

Research on Index System and Algorithm of Customer Classification in Electricity Market from the Regulatory Perspective

WANG Peng, ZHANG Pengyu, GAO Yajing, XU Jingwen, SUN Huakai

2018, 51(12):  139-148.  DOI: 10.11930/j.issn.1004-9649.201708109

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Rational classification of electricity market customers can be used as the basis for market access, market regulation and service strategy. Based on the latest development of electricity market reform, a reasonable classification index system is constructed with consideration of the factors such as renewable energy certificate, demand response and load curve. The two-step principal component analysis (PCA) is used for data dimension reduction to eliminate the repeated information between indicators as well as making the clustering result visible. To deal with the flaws of the traditional clustering algorithms that need to specify the parameters, the advanced affinity propagation (AP) clustering algorithm is used to realize customers clustering. A case study of 40 customers is conducted, which has proved the effectiveness and advantages of the proposed model. Finally, the regulatory design of survival of the fittest is introduced, and suggestions are put forward for customer admittance and management in the electricity market, which are of practical value.

Construction of the Framework for Adaptability Evaluation of Electricity Market

YAN Yu, LIN Jikeng, HOU Yanqiu

2018, 51(12):  149-157.  DOI: 10.11930/j.issn.1004-9649.201807080

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Based on the characteristics of China's power system and the priority of electricity market development, It establishes an integrated adaptability evaluation framework of electricity market. Firstly, an adaptability evaluation index system is built with consideration of four aspects including effectiveness, fairness, security and scalability of the market, and accordingly, multiple secondary indicators are raised to quantify the corresponding electricity market model in a scientific and reasonable way. Furthermore, an evaluation method based on fuzzy evaluation and analytic hierarchy process (AHP) is proposed to realize the quantitative evaluation of the electricity market on the basis of the index system. Finally, based on the proposed adaptability evaluation index system and method, a complete adaptability assessment framework is constructed for the electricity market, which is helpful for the comprehensive assessment of the electricity market and the orderly and sustainable construction of the electricity market.

System Design and Operation Analysis of the Desulfurization Wastewater Treatment with Flue Evaporation Process for a 660 MW Unit

JIN Yinjia, LIANG Xiujin, SUN Haifeng, WANG Fengji, ZHU Yue, JI Haihong, LIN Jingmin

2018, 51(12):  158-162.  DOI: 10.11930/j.issn.1004-9649.201712030

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Due to the high salinity and complex components, the treatment of the flue gas desulfurization wastewater is always a challenge to meet the "zero discharge" standard. Based on the mathematical model and Fluent simulation, the evaporation process of the flue gas desulfurization wastewater with droplet diameters at 50 μm and 60 μm are studied. The two sizes of wastewater droplets are vaporized in 0.78 s and 0.85 s at 130℃, and the compressed air consumptions are 60 m³/min and 26 m³/min, respectively. Moreover, the characteristics of the flue flow field in a 660 MW unit are also considered in the optimization of the wastewater evaporation system design. The operation data of the wastewater evaporation system are collected and analyzed for the further system optimization. Experimental results show that the evaporation of the desulfurization wastewater in the flue does not affect the flue gas desulfurization system and the electrostatic precipitator, and the variation of the fly ash is still within the resource utilization limit.

The Review and Perspective of the Solid Adsorbents Application in the Integrated Flue Gas Pollutants Removal Technology

ZHOU Xujian, LI Qingyi, XU Hao, HU Daqing

2018, 51(12):  163-169.  DOI: 10.11930/j.issn.1004-9649.201712011

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The application of integrated technology is the trend for flue gas pollutants removal in coal-fired power plants. With the simple process as its feature, the solid adsorbents are studied extensively in the integrated pollutants removal technology. Some adsorbents, such as, the carbon-based adsorbents, the calcium-based adsorbents and the CuO/γ-Al₂O₃, which may have good application prospect in the SO₂, NO_x and mercury integrated removal, are reviewed in this paper. The removal mechanisms, research status, application prospect and existing problems for each type of adsorbents are analyzed and summarized. It shows that the mutual influence and interaction mechanism between the different pollutants are still not clear. The future work should focus on the reduction of the adsorbents' cost, the improvement of the by-product utility value, the improvement of the denitrification efficiency and the strengthening of the mercury removal research. Finally, the perspective of the SO₂, NO_x and mercury integrated removal technology by using solid adsorbents is presented to show its significant importance to the pollutants reduction in coal-fired power plants.

Experimental Study on SO₃, HCl and HF Removal Efficiency of Wet Electrostatic Precipitator

WANG Guihua, ZHU Binshuai, ZHANG Haizhen, HAN Haiyan

2018, 51(12):  170-174.  DOI: 10.11930/j.issn.1004-9649.201803020

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In coal-fired power plants, the flue gas after wet desulphurization still contains strong corrosive substances such as SO₃, HCl, HF and so on. Higher requirements are put forward for the corrosion resistance of the chimney even though the content is not that high. The wet electrostatic precipitator installed after the desulphurization has certain removal effect for the corrosive substances. In order to study the removal efficiency of wet electrostatic precipitator, samples were taken from the inlet and outlet flue gas of a metal plate type wet precipitator in a 330 MW unit of a power plant to detect the concentration of SO₃, HCl and HF. It is concluded that the removal efficiency of the wet electrostatic precipitator for the strong corrosive acid gases was 45%, 85% and 65%, respectively. The results show that the wet electrostatic precipitator can effectively remove the corrosive gas in the flue gas and reduce its concentration at the inlet of the chimney, and therefore the corrosion rate of chimney can be slowed down.

Research Progress on the Treatment Technologies of Wet Flue Gas Desulfurization Wastewater in Coal-fired Power Plants

NIE Xiangxin, ZHENG Zongming, CUI Xiaoyang, LU Qiang, DONG Changqing, ZHAO Jin

2018, 51(12):  175-179.  DOI: 10.11930/j.issn.1004-9649.201706196

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The treatment of desulphurization wastewater is one of the challenges hindering further water saving in coal-fired power plants. In this paper, the typical treatment technologies, including triple box treatment, membrane-based treatment, thermal-based treatment and electrolytic treatment are introduced while the characteristics of limestone/gypsum wet desulphurization wastewater are discussed. The future treatment technologies of desulfurization wastewater should integrate pretreatment, concentration and resource utilization process etc. In particular, pretreatment plays an indispensible role in the removal of dissolved calcium and magnesium ions, colloidal particles and inorganic scale components. Specifically, problems such as decrease of permeation flux, decline of heat transfer efficiency and electrolytic efficiency due to polarization of membrane, fouling of membrane, scaling of heat transfer equipment or resistance increase of electrolytic bath can be avoided in the process of concentration and resource utilization by pretreatment. In order to create conditions for follow-up zero discharge treatment, it is suggested that the pretreatment level of triple box treatment should be strengthened from the view of turbidity reduction and water softening.

Design and Analysis of Water Island in Coastal Thermal Power Plant

YE Zhian, ZHANG Jiangtao, SUN Junfeng, MU Shirong

2018, 51(12):  180-184.  DOI: 10.11930/j.issn.1004-9649.201712039

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Thermal power plant water treatment system using the water island construction mode in the water is capable of taking better advantage of the cascading water usage while saving more occupied area and equipment investment. For some coastal thermal power plants that rely on seawater desalination as the industrial water for the whole plant, it is of greater significance to apply the construction mode of the water island. Take a coastal thermal power plant as an example, this paper introduces the idea of water island system design for this type of thermal power plant water treatment system, analyzes the layout and decentralized arrangement in terms of area and economic benefits, then points out the items that more attention needs to be given in the design of water island system. The analysis shows that the centralized deployment of water islands in coastal thermal power plants occupies 20% of the floor area less than conventional decentralized arrangements, and it can also save the investment on a large amount of public facilities. Therefore the target to downsize staff and improve economic efficiency is reached while the level of water regulation is enhanced with significant economic and environmental benefits.