| This paper focuses on the hotspot technical problems of improving the operation flexibility of thermal power plants,in view of the structural characteristics of condensing steam turbine unit transformed into dual rotors and double back pressure cogeneration units,the peak shaving flexibility of these units during heating period was studied.These research is the first time in our country,it will play an important role in broadening the scope of the power grid peaking unit and improving the ability of the combined heat and power generating units to participate in the deepening peaking of the grid,and the development of China’s cogeneration industry.At present,China’s large heating units have the following problems to be solved:(1)The peak shaving capacity participating in power grid during heating period;(2)The heating load demanded by the society continued to increase rapidly;(3)The heating capacity and quick response capability of the heating unit are seriously insufficient,especially in the high cold area;(4)The circulating efficiency of the heating unit still has further improved technical space.In order to solve the above problems,improve the heating capacity of the existing units,in response to national policy of heating unitsflexibilitytransformation and energy-saving and emission-reduction,the condenser unit originally designed to bear the basic load was transformed into a heating unit.In order to improve the capacity of these units to participate in peak load regulation of power grid,four ultra high pressure 135MW turbine units and a 300MW steam turbine unit are selected for demonstration tosystematically study the technical characteristics of condensing steam turbine transformed into dual pressure and double rotors combined heat and water direct heating unit.Then summed up the transformation method and adaptation technology suitable for 135MW unit,300MW unit in their specific structure characteristics,including interchangeability of new and old rotors,interchangeability of couplings,stability of new and old shafts,and expansion reliability of static and dynamic parts.Specific research work is as follows:(1)Collect the main structure characteristics of the four high pressure 135MW steam turbinetransforming into double rotor double back pressure cogeneration unit with circulating water direct heating,including design of new low pressure cylinder with high back pressure,new low pressure rotor with high back pressure,new type high strength last stage blade and adaptive modification of condenser.Sum up the structure characteristics of thesub critical 300MW condensing turbine transformed into two rotors double back pressure cogeneration unit with circulating water direct heating,including general reform of double deck low pressure cylinder,development of new low pressure rotor with high back pressure,new low pressure stage blade,reliability improvement of seat type bearing,improvement of water jet system of shaft seal system and low pressure cylinder,expansion of operating range of steam driven feed water pump,application of high temperature resin in condensate finishing system and adaptive modification of condenser.(2)In this paper,field experiments on peak shaving flexibility and adaptability of the above five units are carried out.According to the transformation characteristics and actual operation ofeach unit,present work determined the test load condition,proposed the conditions for experiment and worked out the experimental procedures and specific implementation plans.During the heating season of 2016-2017,field trials of peak shaving adaptability and flexibility were carried out.The experimental conditions include the initial heating period,the medium heating period and the extreme cold condition.During the test period,in order to accurately analyze the capacity of each unit to participate in peak shaving,the electric load was adjusted under the premise of meeting the heating demand,and a large number of surge regulation adaptability data of each unit were obtained.(3)The peak shaving capacity and limiting factors of above dual back pressure dual rotor heat supply units with different capacitiesand heating modes are analyzed.Then the research on the scheduling flexibility of dual back pressure dual rotor heat supply unit and the promotion scheme of peak shaving capacity are obtained. |
