| In this paper, the dry discharging systems of the 600MW coal-fired generating units # 6 boiler in Zouxian Power Plant will be studied. The control model and system configuration, software implementation of control system and the airport control system of the dry discharging system, and different operating conditions of the boiler efficiency law, etc. are studied.Firstly, the dry discharging operating status and system components of China's coal-fired power plant boiler are analyzed in detail. The advantages and disadvantages of different transportation methods used in the dry discharging systems are summarized. Recommendations and measures are proposed from the technical level. Then, with the author participating Nanjing General Electric Company who assumes transformation projects for the 600MW coal-fired generating units # 6 boiler in Zouxian Power Plant, the dry discharging systems are designed. The component of each subsystem and the relevant technical requirements are identified. On this basis, the dry discharging system of the 600MW coal-fired generating units # 6 boiler in Zouxian Power Plant was designed. The PLC control system and the integration of it in the dry discharging system is implemented, including the PLC control system hardware, software designed. From the dry discharging system of the 600MW coal-fired generating units # 6 boiler in Zouxian Power Plant put into normal operation, the author draws up the thermal performance field test program, and completes the output of the dry discharging systems in different operating conditions, and the test of thermal efficiency of the anti-balance field in #6 boiler in different condition. On the field tests results data collection and analysis, the author analyzes the thermal efficiency and energy savings effecting law in the dry discharging system of the #6 boiler. This research work draws the following main conclusions.(1) The control system of the dry discharging system in Zouxian Power Plant #6 boiler composes of hardware PLC control system as the main. The PC uses IFIX4.5 configuration software. Concept V2.6 XL EN software is used for lower compute with the advantages of many programs in a module. The above configuration of the control system was proved that the control system can meet the requirements of the dry discharging system in control system. The whole system has strong anti-jamming ability, good maintainability, scalability and adaptation to the harsh environment and other significant advantages. The control system of this dry discharging system provides system design, configuration and system implementation as technical basis for other types of 600MW units dry discharging system;(2) Since Zouxin Power Plant Boiler # 6 remould the wet discharging systems into the dry discharging systems, the content of fuel in the boiler slag is basically the same. Under different operating conditions in the boiler, the temperature of the bottom cooling air will rise after cooling the slag in the dry discharging systems. After used, the cooling air flow from the bottom of the boiler into the boiler is generally less than 1% total air volume of chamber. The air temperature, from the dry discharging systems to the bottom of the furnace, measured in different dry discharging systems operating conditions of the field experiment, is between 240℃-326℃. The boiler efficiency increases corresponding 0.107% when the average air temperature entering the furnace is 290.1℃and the air flow which comes from the discharging account the total air volume into the furnace is 0.9%. The average temperature of the critical bottom inlet which influences to the boiler efficiency reduced by the increased transfer is about 262℃. The key that ensures to achieve energy savings after the dry discharging system transformation is rational organization of bottom inlet, the bottom furnace slag into the wind and the full heat exchange;(3) Zouxian power plant # 6 boiler is reformed to design dry slag discharge system by original wet slag discharge system. After operating, the system is safe and reliable with fully meeting the requirement of slag discharge in normal operation condition. Comparing to the original wet slag draining system, this dry slag discharge system can save water about 25.9 tons annually and save power about 65.81 million degrees. As a result,213.285 million yuan of coal about 900 tons can be saved annually. More importantly, the investment of dry slag discharge system can be reclaimed in 4 years.The result of this paper shows that dry discharging system can be used in high capacity machine units of coal-fired power plants in China. They also produce energy-saving and emission-reduction and social benefits. So they have commercial competitive ability. They owe practical popularize value for dry slag discharge system transformed, designed and operated in large and medium-sized plant coal boilers in China. |
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