Integrated Intelligent Energy

Technical and economic analysis on the energysaving renovation by the waste heat deep recovery of a 300MW coalfired unit

ZHU Wentao，LIANG Xiujin，ZHU Yue

2018, 40(9): 1-4.

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In the energysaving renovation of a 300MW coalfired unit by recovering the waste heat deeply. There are 4 different energysaving renovation plans distinguished by different arrangement positions and different texture of heat exchanger, as well as the effect on induced draft fan and force draft fan. It demonstrated the feasibility of the 4 types of energy saving renovations on the waste heat deep recovery, by comparing their technology, technical economy analysis, cost analysis and the payback period. And it can provide reference for similar reconstruction projects in the future.

Comparative analysis of design schemes for wet plume removal in coalfired power plant

WANG Zhengrong, GENG Xuan, WANG Yang, XIA Huaipeng, FU Lihui, SHEN Mingzhong, SHEN Jianyong, WANG Kailiang

2018, 40(9): 5-9.

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The moisture in flue gas after WFGD would be precipitated and form a wet plume at the chimney outlet, which causes certain visual pollution. By analyzing the mechanism and treatment of wet plume, the effects of ambient temperature and humidity on the elimination of wet plume are discussed. The effect of techniques on eliminating the wet plume of a power plant is compared and analyzed between flue gas heating, flue gas cooling, and flue gas cooling plus reheating. The technique which includes cooling, indirect heat exchange and hot secondary air mixing is the most suitable one. In addition, the cooling plus reheating scheme of a power plant is analyzed. When the temperature of flue gas shellandtube heat transfer decreases 3，5， and 7℃, the economic recovery period of the combination of cooling heat exchangers and reheat exchangers with different materials and various types are compared. The overall static recovery period of the wet plume elimination is shortened with the decrease of the temperature of cooling section, and the combination of the widechannel platetype condensing heat exchanger and the widechannel platetype reheater is the most economic.

ANSYS analysis of wet electrostatic precipitator placed on top of desulfurization tower

XIA Huaipeng, WANG Yang, ZHAO Bing

2018, 40(9): 10-14.

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The finite element analysis on the structure of the wet electrostatic precipitator placed on the top of the desulfurization tower was carried out by ANSYS. The results show that the opening on the wall of the desulfurization tower causes concentration points of structural stress and weak parts of tower. According to the results of finite element analysis, reasonable tower wall thickness and construction measures are selected to achieve design optimization.

Neutral test on the utilization of ceramic UF in circulating cooling wastewater in coalfired power plant

YANG Qitao1，LI Xinwang2, PENG Kangming2

2018, 40(9): 15-17.

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Circulating cooling wastewater is one of the main sources of industrial wastewater of coalfired power plant. Its recycling process and equipment have been popular in wastewater zero discharge study in recent years.Taking the circulating cooling wastewater of Huadian Tengzhou Xinyuan Thermal Power Company Limited, neutral test is carried out with softened clarifiers and ceramic ultrafiltration equipment under specific operating parameters and conditions.The accumulated data prove that cooling wastewater softened and clarified by equipment with ceramic UF membrane, can keep its flux at 260L/(m2·h)stably.The chemical maintenance cleaning cycle is 12 hours.The turbidity of permeate should be less than 0.2 NTU and SDI should be less than 3.The effluent completely meet the requirements of reverse osmosis.The ceramic UF system can work well with high operating flux,operational stability and good water quality.

Analysis and countermeasure of oil leakage in QFR480 generator

YANG Xutao

2018, 40(9): 18-20.

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Two oil leakage cases of Dongfang Mitsubishi QFR480 gas turbine generator are introduced. The causes and troubleshooting methods for unsmooth hydrogen side oil return of the sealoil system are analyzed, and the preventive measures are put forward to improve the reliability of the generator operation.

Optimization and modification of condensing steam turbine

ZONG Xudong

2018, 40(9): 21-24.

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Condensing steam turbine accounts for the largest proportion of heating units in China. Due to design, modification, operational adjustment and other reasons, there are a series of problems affecting the safety and economy of the units. Combining with examples, typical problems and causes during heating supply are analyzed from the security monitoring, protection devices configuration, heating regulation and other aspects. Comprehensive optimization program can not only ensure the safety of heating units, but also reduce the throttling loss during steam supply.

Discussion on the problem of power supply with different grids in thermal power plant

ZHU Hao

2018, 40(9): 25-27.

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The power grid for supplying and the standby transformer power grid of UHV transmission units may be connected to 2 regional power grids, which brings problem to switching and operating between station service power supply and standby power supply. Through research and analysis, it is recommended to place a generator circuit breaker to avoid problems when station service power supply is shut off and switched to another grid. During the abnormal operation of high/low voltage systems of factory service power supply, nonsynchronous parallel switch can be added in the closing circuits to help contact to interlock. The closing circuit with decentralized control system, logic blocking and criterion from the same grid, can not only meet the parallel switching requirements on the factory lowvoltage system when the operating mode changes, but also prevent the nonsynchronous parallel accident.

Measures to improve heating capacity of thermoelectric gas turbine in South Xinjiang Thermal Power Plant

ZHENG Liwen

2018, 40(9): 28-29.

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There is a gassteam combined cycle thermoelectric unit in Tianjin Huadian Nanjiang Thermal Power Plant, with advantages of efficient energy utilization and low polluted emission. However, the heattoelectric ratio is small, and the heating capacity is worse than that of coalfired power plant with same generating capacity. The heat load in the area is large. In the process of design and construction, ‘two plus one’ installing scheme, back pressure steam turbine, the expansion of the low pressure economizer and heat/pressure reduction of HRSG in the full cutting time of the steam turbine are taken. The measures improve the heating capacity, heating reliability and heat efficiency of the unit.

Problems and preventive measures for steam turbine safety monitoring system equipment

LIU Qiang

2018, 40(9): 30-31.

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In the turbine supervisory instruments (TSI) of Anhui Huadian Wuhu Power Generation Company Limited, there are problems such as excessive temperature of DC power supply module and poor contact with the extension plug of vibration sensor. Through analysis, replacement with a more stable power supply module, optimization of the sensor connector and dispersing the arrangement of vibration measuring points are proposed, which improves the reliability of measurement and protects of the TSI system.

Fire issues and countermeasures of flue gas treatment facilities in thermal power plant

DU Wenhua, WANG Wei

2018, 40(9): 32-33.

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Taking a thermal power plant under construction as an example,it introduces the basic process of flue gas desulfurization,denitrification and dust removal facilities,and analyses the fire issues existed in the infrastructure construction and operation period.Considerations on fire protection facilities are taken while dealing with the flue gas treatment of thermal power plants.With practitioners’ attention,the fire issue can be avoided.

Research on operation mode seamless switch between microgrids by microcomputerbased device

LI Peiyi, OUYANG Yifeng, LI Yan, SUN Pan

2018, 40(9): 34-37.

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Microgrid is currently in the demonstration stage in China. A switching mode for microgrid operation controlled by microcomputerbased devices is proposed to realize seamless switching between gridconnected operation and offgrid operation, which can reduce the impact on the grid while switching. The method has been verified by the laboratory and has reference to practical project.

Analysis on the steam extraction retrofitting of heat supplied unit

LIU Li, XU Wei, CHEN Xiao，CHEN Xin, WANG Naibing

2018, 40(9): 38-39.

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In order to improve the heating capacity of the heat supplied unit, the unit needs to be retrofitted. Compared with different steam extraction schemes, the one that uses intermediate valve to control hot reheat steam is feasible, which can meet the needs of users for high temperature and high pressure steam under low load operating conditions. After the transformation, the economy and safety of the unit is analyzed. The results show that with decrease of the load, the main steam flow increases, the efficiency of the high pressure cylinder increases, the efficiency of the medium pressure cylinder decreases and the inflow to mediumpressure and lowpressure cylinder is slightly reduced, the power consumption of the auxiliary machine is slightly increased, and the vibration and axial displacement of the unit are satisfied.

Analysis and treatment on vibration faults diagnosis after flow path retrofitting of 600MW steam turbine

CHEN Jie, ZHAO Weizheng

2018, 40(9): 40-43.

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Vibration problems during the startup and operation period are found in some 600MW steam turbine units in Zhejiang Province after the flow path retrofitting. Causes of vibration faults of different units include mass imbalance, resonance and low accelerate ratio at overcritical speed. Countermeasures of these problems are given, which provides a reference for engineers and designers of the retrofitting.

Adjustment process of gland sealing clearance of 600MW steam turbine full solid cylinder

YU Yong

2018, 40(9): 44-46.

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The clearance of gland sealing is one of the main factors affecting the thermal efficiency and thermal economy of the steam turbine. The adjustment of the center of cylinder bore on the diaphragm will directly affect whether the clearance of gland sealing will meets the standard, and the vertical arc of cylinder is the key to the center of cylinder bore and gland sealing. The key factor in the adjustment of the clearance is analyzed. It discusses the optimization process of adjusting the center of cylinder bore and gland sealing of fullsolid cylinder during the overhaul of the 600MW steam turbine in Sichuan Huadian Gongxian Power Generation Company Limited. The onsite inspection shows that the optimization and adjustment of the gland sealing clearance achieved satisfactory results, improved the efficiency of the maintenance of the turbine body, and ensured the economy and safety of the unit after overhaul.

Analysis and treatment on high wheelspace temperature of 9E gas turbine

DAI Huiqing1，JIN Hao2，ZHOU Renmi3

2018, 40(9): 46-48.

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There was fault caused by high wheelspace temperature of a 9E gas turbine after the oil and gas systems reformation. After preprocessing and analysis, it was suspected that the fault was caused by uneven radial clearance and the leakage of high temperature gas to the secondstage nozzle. By adjusting the bearing height, the radial clearance of the whole shaft system was uniform. After the restart with load, the problem of the high wheelspace temperature disappeared, the safe and stable operation of the gas turbine is ensured.

Application analysis of the automatic bypass of primary fan frequency converter

DU Zhiqiang

2018, 40(9): 49-50.

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A frequency converter of a company is equipped with automatic bypass conditions, but without switch scheme. Therefore, the automatic switch to the bypass cannot be realized when there is fault in frequency converter，which brings hidden trouble to the safety of the units. Taking an automatic bypass of the primary fan in 2×350MW units as an example, it analyzes the feasibility. The analysis provides automatic bypass scheme for the frequency converter of the company. 

Comprehensive governance of coal handling system in Xisaishan Power Generation Company Limited

WEI Wei, WU Fenglin, WANG Gang

2018, 40(9): 51-54.

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Due to the aging of the coal handling system in the first stage of Hubei Huadian Xisaishan Power Generation Company Limited, the concentration of dust in the transfer station is quite high during the operation. The deviation of the belt, scattering of coal and the excessive concentration of dust are resulted from impropriate feeding point. With the change of the source of coal, the original coal handling system process seriously constraints the efficiency of production. Optimization is performed on coal handling process through reforming the transfer station, and optimizing the coal handling system equipment by using the curving coal dropping pipe and dust suppression guide trough at the same time. An automatic dust concentration monitoring and controlling system are added. The dust concentration in the transfer station can be reduced by methods such as utilizing the dustreducing equipment, which is analyzed by realtime data. Methods improve the working environment, improve the transportation efficiency, and obtain good economic and social benefits.

Reduce the emission of soot caused by heating in the northern rural areas during winter by increasing the utilization hours of stocked thermal power

LE Jianhua, LIU Jinxiong

2018, 40(9): 55-60.

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It analyses the data of soot emission which is a cause of smog. It is confirmed that the soot emissions from bulk coal are 150～330 times that of coalfired power plants (2017 data).To control the smoke and dust during winter in the northern rural areas, corresponding measures should be taken. Comparing the emission of thermal power and bulk coal, the policy that ‘admission of great capacity and rejection of small capacity’ has become history. The emission of stocked thermal power is almost equal to that of gas generating. Considering the cost and external dependence of these two generating methods, it proposed that it is the bulk coal that should be taken place by natural gas, instead of the coal. Based on the status quo that utilization hours of stocked thermal power is less than 4300h and there is subsidy for ‘switching from coal to electricity’ currently, it proposes to increase the utilization of stocked thermal power, to subsidize farmers with tiered electricity prices and to replace the bulk coal in northern rural areas. Full use of resources can be made and environment can be improved with electricity prices transferring. It provides a new way to control the emission of soot, an important cause of smog.

Research on ammonia spraying optimization in SCR denitrification system

FANG Mingcheng, LIU Yuqiang, WANG Runming, ZHOU Ming

2018, 40(9): 61-65.

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In order to improve the performance of denitration, reduce ammonia escape rate, reduce the risk of air preheater blockage and meet the environmental requirements of low emission standards, the optimization experiments on ammonia spraying for SCR denitrification system of a 2×330MW coalfired power plant are studied.The distribution deviations of NOx concentration at the SCR denitrification system outlets of #1 and #2 units decreased 29.6% and 45.2% respectively after the optimization. The mass concentrations of ammonia slip were declined by 0.418mg/m3 and 1.786mg/m3 on average. The amounts of ammonia by the SCR device were regulated by adjusting the opening of ammonia injection valve, which improves the distribution uniformity of NOx mass concentration at the outlet of SCR denitrification system significantly, eliminates the peak of localized peak of ammonia slip and reducing the ammonia slip rate.

Analysis on the influencing factors of thermal power consumption of power generation for S109FA combined cycle units

LI Zhixin

2018, 40(9): 66-69.

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:Based on the actual operation conditions of two 390MW S109FA gassteam combined cycle generating units of a power plant in Guangzhou，it analyses the major influencing factors of thermal power consumption rate of power generation. According to the query function of historical data in PI database, quantitative analysis can be made on the influence of these factors through practical cases. The quantitative analysis result proves the availability of the analysis method above. At the same time，the result of analytic procedure provides calculating basis for the quantitative analysis on the features of variable working condition of the units.

Comparative analysis on two combined systems with air heater and lowpressure economizer

ZHOU Zhou, LIU Nan

2018, 40(9): 70-71.

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Taking a 300MW unit as an example, compared the classic layouts and energysaving schemes of two combined systems with air heater and lowpressure economizer. Through theoretical analysis, the differences of coal consumption between 2 schemes is 0.89g/(kW·h) under heat consumption acceptance condition ,which can provide a reference for the power plant which is willing to carry out a similar transformation.

Analysis of renewable portfolio standard

JI Yunsong1, GE Wengang2

2018, 40(9): 72-76.

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The development mode of renewable energy has been a problem worldwide. The government subsidies are being placed by the market. Mandatory quotas have been proposed many times but have not been implemented domestically. Reviewing the history of domestic quota system, and analysing recent drafts on quotas and assessment methods at the same time, the feasibility of drafts has been proved but relevant problems have also been raised.

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