Coal powder boiler commissioning

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Commissioning of pulverized coal boilers 1. Overview Boiler commissioning includes the commissioning of the coal grinding system, cold-state testing of the boiler, full-scale startup testing of the boiler, and combustion adjustment tests. The combustion conditions of the boiler have a significant impact on the economic efficiency and safety of both the boiler equipment and the entire power plant. Proper adjustment of the combustion conditions, namely complete fuel combustion and a uniform temperature field and heat load distribution in the furnace, are essential conditions to ensure the safe, stable, and economical operation of the boiler. 2. Test Methods 2.1 In view of the characteristics of coal-fired boilers, tests shall be conducted in accordance with GB10184--88 \"Code for Performance Tests of Power Station Boilers\", \"Test Code for Coal Grinders\" (DL467-92), or ASME Test Codes PTC4.1 and PTC4.3, as well as relevant testing methods ； 2. During the combustion adjustment tests, with the boiler and auxiliary equipment operating normally and the load remaining relatively stable, various combustion conditions are thoroughly measured by systematically changing certain adjustable parameters and control methods. Analyses and comparisons are conducted from various aspects such as economic efficiency and safety, in order to determine the optimal operating conditions. 3. Test conditions and requirements 3.1 During the test, the boiler shall use coal of a type suitable for long-term operation, with relatively stable coal quality ； 3. During the 2,3-hour test period, the main parameters of boiler operation should remain basically stable (within the range of variations permitted by the regulations); no operations such as slag removal, soot blowing, coking removal, or any other actions that could disrupt normal operating conditions shall be carried out ； 3.3 The main operating instruments of the unit provide accurate readings; the automatic control system and flame detection systems operate reliably. All the instruments and equipment required for the tests are ready, and all the testing points have been installed and found to be in good condition after inspection ； 3. During the 3rd and 4th tests, the operators and testers must work closely together; in the event of an emergency during the testing process, actions shall be taken in accordance with the established procedures ； 3, 5 To ensure the smooth progress of the tests, cooperation and support from departments such as the power plant’s maintenance team, fuel testing unit, and thermal instrumentation team are also required. 4. Test Content 4.1 Commissioning of the coal grinding system 4.1.1 Purpose and significance Through tests on the coal grinding system, it is possible to understand and grasp the characteristics of its equipment, adjust the system to operate in a safe and economical manner, provide operational guidelines for staff, and determine the maximum output of the coal mills as well as the optimal operating conditions for the coal grinding system based on these adjustment tests. 4. Main contents of tests 1 and 2: There are mainly two types of coal grinding systems, namely the intermediate storage coal grinding system and the direct-blowing coal grinding system. The commissioning methods for the two types of grinding systems differ, as described below: (1) Intermediate silo-type grinding system ※ Preliminary tests ； ※ Calibration test of the coal feeder’s coal supply rate ； ※ Experiment on the optimal steel ball loading amount for coal mills ； ※ Characteristics test of the inlet baffle in the coarse powder separator ； ※ Optimal ventilation rate test ； ※ Powder production system output test ； ※ Tests on the optimal operating conditions of the coal grinding system (2) Direct-fired coal grinding system ※ Flow rate deviation of the primary air duct and calibration test of the back duct ； ※ Calibration of the wind measurement device at the coal mill inlet ； ※ Separator baffle characteristic test ； ※ Coal grinder output test ； ※ Variable air volume performance test ； ※ Loading pressure test ※ Coal powder distribution performance test. 4.2 Cold-state commissioning of the boiler 4.2.1 Purpose and significance Cold-state commissioning should be carried out prior to the combustion adjustment tests. The purpose of cold-state commissioning is to understand the actual condition of the equipment, identify any defects present, so that they can be addressed promptly ； Understanding the cold-state operating characteristics of boilers and their associated auxiliary equipment, as well as predicting their hot-state operating characteristics, provides a basis for operational control during boiler startup and normal operation. Cold-state tests are the foundation for boiler operation and hot-state tests, and they ensure the successful ignition and stable operation of the boiler. 4. 2.2 Main debugging contents (1) Equipment inspection ※ Check the sealing performance of the supply and exhaust air systems. Leaks in the air supply and exhaust systems are factors that compromise the safety of power plants, and they also hinder their efficient operation ； ※ Check the adjustment characteristics of the damper plates: First, verify whether the adjustment of the damper plates is smooth ； Second, check whether the actual position of the baffle matches the external indicated position ； ※ Verify whether the air volume and air pressure of the supply and exhaust fans meet the parameters specified on the nameplate, and whether they satisfy the requirements for boiler operation ； ※ Cold-state mechanical inspection of the burner. The burner is an important component of a boiler’s combustion system, and its proper functioning has a direct impact on the efficiency of the boiler’s combustion process ； ※ Check the adjustment characteristics of the damper plates: First, determine whether the damper plates adjust smoothly ； Second, check whether the actual position of the baffle matches the indicated external position. (2) Calibration of the air flow measurement device: The accuracy of the boiler’s air flow measurement directly affects the correctness of the operators’ control over the boiler’s operation, and it is related to both the safety and efficiency of boiler operation; the results of calibration are used to adjust the instruments. It mainly includes the calibration of the flow coefficient of the measurement devices for primary, secondary, and tertiary air. (3) Baffle opening characteristic test: Mainly the secondary air baffle opening characteristic test. (4) Air distribution uniformity test: It mainly involves adjusting the air volume of the primary, secondary, and tertiary air streams to ensure uniformity across the four corners of the same layer. Ensure uniformity in the air volume supplied from each burner to avoid incomplete combustion and coking due to high temperature and low oxygen levels. (5) Test on the flow velocity distribution characteristics in horizontal flues, primarily to measure the velocity deviations of the flue gas in vertical, horizontal, left, and right directions. (6) Boiler cold-state aerodynamic field test – The main observations regarding the burner jet during normal cold-boiler tests: ※ The range of the jet, as well as the velocity decay along the axis ； ※ Size and position of the tangent circle formed by the quadrilateral jet ； ※ I. Mixing characteristics of primary and secondary air, such as the mixing distance of the primary and secondary air streams from the nozzles, as well as the relative deviation of each stream ； ※ The effects of changes in the nozzle inclination angle on the jet mixing distance and its degree of relative deviation, etc. In cold-state tests, the main aspects observed regarding the airflow in the furnace are: ※ The degree of filling of the furnace by flames or airflow, which is generally expressed as the ratio of the cross-sectional area occupied by the effective airflow to the total cross-sectional area of the furnace. The greater the flame fill factor, the higher the utilization rate of the furnace chamber, and the smaller the eddy current zones in the stagnant areas within the furnace. ※ Observe the gas flow dynamics inside the furnace. First, it is necessary to check whether the airflow is scouring the furnace walls; if the airflow stays close to the walls, the tubes may suffer from corrosion, and coking is likely to occur inside the furnace ； Second is the uniformity of air flow distribution across the furnace cross-section; there should be no deviation. If the air flow leans to one side of the furnace, it can lead to excessively high flame temperatures on that side, severe soot formation, as well as uneven heat loads on the heated surfaces and uneven superheated steam temperatures. ※ Various interference scenarios between air flows, such as the mutual influence between burner jets and the effect of tertiary air on the main burner jet. 4.3 Thermal combustion adjustment tests and performance testing of boilers 4.3.1 Objectives and significance Combustion adjustment tests involve systematically changing certain adjustable parameters and control methods in order to conduct comprehensive measurements of the combustion conditions. The obtained results are then subjected to scientific analysis, and comparisons are made from various aspects such as safety and cost-effectiveness to determine the optimal operating mode, after which performance tests are conducted under this condition. At the same time, comprehensive combustion adjustment tests can yield the technical and economic characteristics of the boiler under its optimal operating conditions; they can also help identify specific issues that affect the safe, stable, and economical operation of the boiler, allowing for the determination of causes and the development of solutions. 4. 3. 2 Main debugging tasks: (1) Adjustment of fuel supply uniformity among burners: Adjusting the amount of coal powder supplied to each burner layer so that the coal consumption per burner in the same layer is roughly similar is necessary to ensure a uniform heat load in the boiler ； (2) Adjustment of air distribution method: By changing the ratio of primary and secondary air, as well as using air volume control dampers at different positions, the speed at which primary and secondary air enter the furnace and the distribution of air volume in various areas can be adjusted, in order to determine the optimal secondary air supply rate and air distribution method. (3) Coal powder fineness test: By changing the fineness of the coal powder, the operation of the boiler is observed, and at the same time the boiler efficiency as well as the smoke temperature distribution in the furnace are determined, in order to find the optimal coal powder fineness value suitable for the boiler’s operation ； (4) Adjustment of excess air coefficient: An excessive total air supply to the boiler increases its heat losses due to flue gas; too little air, on the other hand, increases the heat losses associated with incomplete combustion and mechanical losses. There is an optimal excess air coefficient that minimizes the total heat losses of the boiler. Change the total air volume fed into the furnace, measure the boiler efficiency, and determine the optimal excess air coefficient ； (5) Load characteristic test: By varying the boiler load, the economic performance indicators of the boiler under different loads are measured, in order to understand its load characteristics and determine the appropriate operating mode for the boiler at various loads ； (6) Boiler performance testing under optimal operating conditions: By making the above adjustments, the optimal operating conditions for the boiler are determined. Under these conditions, the boiler’s thermal performance parameters are tested, allowing for comparison with the design specifications of the boiler. This helps to understand the equipment’s condition and capabilities, providing a basis for production management and facilitating the improvement of the equipment ； (7) Test on the minimum steady combustion load without oil injection: Determine the minimum steady combustion load without oil injection, as well as parameters such as the air supply method at low loads, the operation mode of the burners, and the optimal coal powder fineness. 5. Analysis and processing of test results: The test results are properly processed and scientifically analyzed, and comparisons are made from various aspects such as economy and safety. This enables the determination of the best performance parameters for the boiler under its current conditions, the identification of the optimal operating conditions for different loads, as well as the creation of operation charts. Effective measures or improvement plans to further enhance the economic efficiency of the boiler unit are then identified through analysis. Appendix: Key Achievements 1 300 MW Class Pulverized Coal Boiler 1.1 Completed the commissioning of the pulverization system for the first domestically produced 300 MW natural circulation drum boiler at Zouxian Power Plant in Shandong; carried out cold and hot state tests, as well as tests on the thermal deviation characteristics of the superheater and reheater, and tests on the wall heat flux. By conducting adjustment tests to bring the unit into an optimal operating condition, this furnace won the **Gold Award** and successfully passed the **level** appraisal ； 1.2 The pulverization system of the DG1025/18.2-4 type quadrangle cut-circle coal-fired boiler at Weifang Power Plant in Shandong was completed in terms of commissioning, startup testing, combustion optimization adjustments, as well as tests on the thermal deviation characteristics of the superheater and reheater. All performance metrics exceeded the design specifications, and this boiler set a record for the shortest commissioning time among units of the same type in Shandong’s power grid; it was recognized as an optimized boiler meeting the standards set by both the Machinery and Electricity sectors ； 1.3 The commissioning and combustion optimization of the 300 MW coal-fired boiler at Shuyangshan Power Plant in Henan were completed; all performance indicators exceeded the design specifications, and the plant successfully passed the performance testing required for certification ； 1.4 The cold and hot condition adjustment tests for the 2×300 MW coal-fired boilers at the Sanmenxia Thermal Power Plant in Henan were completed, improving the efficiency of the boilers and creating conditions for their safe operation ； From December 2002 to March 2003, tests on the cold-state aerodynamic field and combustion adjustment of Unit 1 were conducted once again, and improvement measures were proposed to address the overheating issue in the reheater system ； 1.5 Completed the combustion optimization adjustment for the 2×300 MW coal-fired boilers at Jiangsu Pengcheng Power Plant; all performance indicators exceeded the design specifications, enabling the successful passage of the performance acceptance tests and placing the plant among the top performers in national evaluations ； 1.6 The commissioning of the powder preparation system for the \"W\"-type flame boilers in Units 3 and 4, each with a capacity of 300 MW, at the Hebei Shang’an Power Plant was completed. Tests related to startup, cold-state operation, as well as a series of combustion optimization adjustments were carried out. These boilers are able to operate at full load in a safe, stable, and economical manner. They also passed the performance acceptance tests conducted by the Xi’an Thermal Power Research Institute under the Ministry of Electric Power, thus serving as a model project for Dongfang Boiler (Group) Co., Ltd. in successfully adopting Fosler Wheeler technology ； 1.7 Completed the commissioning of the pulverizing system for the \"W\"-type flame boilers in Units 1 and 2 of the 300 MW power plants at Yangquan No. 2 Power Plant in Shanxi, as well as the startup tests, cold-state tests, combustion optimization adjustments, and thermal deviation tests for the superheaters and reheaters. The boiler efficiency has **increased**, greatly improving the economic viability of the boiler unit, and it passed the performance testing requirements successfully ； From July to December 2002, further commissioning of the pulverizing system for Boiler No. 2, cold-state tests, and combustion optimization adjustments were carried out. Guidance was provided during the overhaul to address any defects in the equipment, ensuring the efficient and stable operation of the boiler ； 1.8 Completed the cold-state tests for the 2×300 MW boilers at Qujing Power Plant in Yunnan, and participated in the hot-state tuning tests and performance acceptance tests for the boilers ； 1.9 Participated in the combustion adjustment tests and performance acceptance tests for the 2×300 MW boilers at Weihai Power Plant in Shandong Province ； 1.10 Participated in the combustion adjustment tests and performance acceptance tests for the 2×300 MW boilers at the Shantou Power Plant in Guangdong ； 1.11 Participated in the combustion adjustment tests and performance acceptance tests for the 4×300 MW boilers at Zhanjiang Power Plant in Guangdong ； 1.12 The combustion adjustment tests for the 4×300 MW coal-fired boilers at Shaanxi Baoji No. 2 Power Plant, as well as the thermal deviation characteristic tests for the superheaters and reheaters, were completed. Boiler efficiency was **improved**, and the plant passed the performance testing requirements successfully ； 1.13 The combustion adjustment tests for the 2×300 MW coal-fired boilers at Guang’an Power Plant in Sichuan, as well as the thermal deviation characteristic tests for the superheaters and reheaters, were completed. Boiler efficiency was **improved**, and the plant passed the performance testing requirements successfully ； In 2002, a successful modification was carried out on the primary air burners of the boiler. After the modification, comprehensive tests were conducted to optimize the cold-air dynamics field and combustion conditions, which completely resolved the problems existing in the combustion system and earned recognition and praise from the users ； 1.14 The combustion adjustment tests for the \"W\"-type flame boilers in the first phase of the 2×300 MW units at Anshun Power Plant in Guizhou were completed, **improving the economic efficiency of the boiler units. Currently, the cold-test and combustion adjustment tests for the \"W\"-type flame boilers of the second phase’s 2×300 MW units are being carried out, to lay a solid foundation for the performance acceptance tests ； 1.15 Completed the startup, cold-state, and hot-state commissioning tests for the 4×325 MW fuel and gas boilers at the Akra Power Plant in Iran. Several issues encountered during the startup process were resolved, which contributed to the smooth startup and successful trial operation of the units. This ensured the successful passage of the performance acceptance tests, earning recognition and praise from the users ； 1.16 Completed the startup, cold-state, and hot-state adjustment tests for the 300 MW \"W\" flame boiler at Shaoguan Power Plant, improving the economic efficiency of the boiler unit and ensuring the successful passage of the performance acceptance tests ； From October 2002 to the present, a comprehensive optimization of the pulverizing system, cold-air dynamics tests, and combustion adjustment tests have been carried out on this furnace ； 1.17 The cold-state modular testing and numerical simulation of the horizontal rich-lean burner for large coal powder boilers were completed; the technical characteristics and operational performance of this burner were understood and mastered. Furthermore, an optimized design for this burner was developed, resulting in a horizontal rich-lean coal powder burner with an innovative structure ； 1.18 The selection design of horizontal rich-lean burners for the 300MW coal-fired boiler at the Liyujiang Power Plant, as well as the cold-state modular testing, were completed. Currently, cold tests, startup trials, and combustion adjustment tests are being carried out on the boiler to prepare for the performance acceptance tests ； 1.19 Current operations include the startup, cold-state, and hot-state tuning tests for the 300MW \"W\" flame boiler at the Hunan Zhuzhou Power Plant ； 1.20 Current research includes experiments on the hydrodynamic instability of the water wall in large supercritical boilers, studies on methods for calculating the mechanical stress concentration factors and thermal stress concentration factors of major thick-walled pressure-bearing components, investigations into the heat transfer and flow characteristics of the coiled tubes in the boiler water wall system, and experiments on the startup characteristics of boilers ； 1.21 Research on the dynamic characteristics of boilers in 600MW units is currently in progress ； 1.22 Current efforts are focused on the digestion, absorption, and development of technology related to dual-air-regulation swirl burners for large-capacity, high-parameter boiler units ； 1.23 The research on boiler selection for Dongfang ultra-supercritical units was completed. 1.24 Technical preparations and specialized research are currently underway for the testing and optimization of boiler startup and combustion in the Datong 2×600MW subcritical units. 1.25 Technical preparations for conducting experiments and studies on boiler startup and combustion optimization for the 2X600MW supercritical units at the Henan Qinbei Power Plant, as well as specialized research on domestic development (four key research projects), are currently in progress. 1.26 Research on combustion technology, as well as preparations for startup and combustion optimization tests, are currently in progress for the boilers of the 2X600MW subcritical units fueled with olefinic oil at Zhanjiang Power Plant in Guangdong. 2 Coal-fired boilers of 2,000 MW and below 2.1 The combustion adjustment tests for the 200 MW liquid slag discharge boiler in Unit 21 of Baima Power Plant, as well as tests on the thermal deviation characteristics of the superheater and reheater and on the dynamic characteristics of the water cycle, were completed; the boiler passed the **-level appraisal successfully ； 2.2 Completed the commissioning of the coal grinding system for the 200 MW boiler at Huaibei Power Plant, including cold and hot state tests, combustion optimization adjustments, and tests on the thermal deviation characteristics of the superheater and reheater ； 2.3 Completed the commissioning of the coal grinding system for the 200 MW boiler at Jingyuan Power Plant, as well as tests for optimizing combustion in cold and hot conditions ； 2.4 The cold and hot combustion adjustments for the 2×210 MW gas turbines at the Chittagong Power Plant in Bangladesh were completed, enabling the successful passage of the performance acceptance tests ； 2.5 The cold and hot condition adjustment tests for the 210 MW oil-gas furnace at the Gudu Power Plant in Pakistan were completed, and it passed the acceptance inspection by the Pakistani side successfully ； 2.6 The cold and hot condition adjustment tests, the thermal deviation characteristic tests for the superheater and reheater, as well as the water circulation dynamic characteristic tests for the first phase of the Shuyangshan Power Plant’s 2×200 MW peak-shaving units were completed, and these units successfully passed the appraisal tests conducted by both the mechanical and electrical departments ； 2.7 Completed the cold and hot condition adjustment tests for the 200 MW fuel-fired boilers at Shandong Xindian Power Plant and Hubei Qingshan Power Plant ； And participated in the boiler performance acceptance test at Shandong Xindian Power Plant ； 2.8 Completed the cold and hot state optimization and adjustment tests for the 200 MW boiler at the Yangzhou Power Plant in Jiangsu ； 2.9 Completed the combustion adjustment tests for the 220t/h boiler in Indonesia, enabling the successful passage of the performance acceptance tests ； 2.10 Completed the cold-state commissioning and hot-state combustion adjustment tests for the 65t/h boiler in the captive power plant of Guangdong Yunfu Hengdali Cement Factory ； 2.11 The combustion adjustment tests for the 2×220t/h coal-fired boilers at the Kuching Power Plant in Malaysia were completed, enabling the successful passage of the performance acceptance tests ； 2.12 Completed the combustion adjustment test for the 75t/h bagasse furnace at Guangdong Yangqing Sugar Factory ； 2.13 Completed the combustion adjustment tests and thermal deviation characteristic tests for the 300t/h boiler at Huaying Mountain Power Plant, and **solved the problem of low main steam temperature in the boiler ； 2.14 Completed the combustion adjustment tests and thermal deviation characteristic tests for the 220t/h boiler at Huaiyin Power Plant, and **solved the problem of low main steam temperature in the boiler** ； 2.15 Completion of combustion adjustment tests and performance tests for Boilers No. 4 and No. 5 at Guizhou Panxian Power Plant ； 2.16 The water circulation test for the 200MW boiler at Jingyuan Power Plant was completed from August to October 2002 ； 2.17 Completed the renovation of the superheater in the 35t/h chain grate boiler at Guangxi Guofa Lin Papermaking Co., Ltd., as well as the combustion optimization tests after the renovation, **to resolve the issues existing in the boiler ； 2.18 Design and manufacturing of 220/9.81-M boiler burners in Zhengzhou, Henan are in progress ； 2.19 The burner renovation for the 170t/h boiler at Shandong Wendeng Power Plant was completed. Currently, cold-test of the boiler following burner modification and combustion optimization adjustments are being carried out ； On 2.20, the cold and hot state commissioning of the 125MW boiler at Guangdong Yunfu Power Plant, combustion optimization tests, as well as tests on the thermal deviation characteristics of the superheater and reheater were completed, enabling the boiler to pass the performance acceptance tests successfully ； 2.21 Participated in the boiler performance acceptance test at Guangdong Hengyun Power Plant ； 2.22 Participated in the boiler performance acceptance tests at the Kashgar Power Plant and Tacheng Power Plant in Xinjiang ； 2.23 The economizer renovation of Boiler No. 6 at Xinjiang Hongyanchi No.1 Power Plant was completed; as a result, the flue gas temperature decreased by 25°C, **improving the boiler’s efficiency ； 2.24 Completion of the cold-state modeling test of the inlet flue for the waste heat boiler at Shenzhen Fuhuade, as well as research on the stress testing of the suspension rods ；