Research On Heat Exchange Law Of Air-Cooled Turbo-generator With Single Channel Ventilation

In recent ten years,with the task of energy-saving and emission-reduction becoming more and more stringent in our country,China has shut down some less efficient,smaller capacity power plants.New turbo-generator which has smaller size and higher efficiency gradually replaced the original design model.Many manufacturers are redeveloped the capacity of 10MW-150MW air-cooled turbo-generator.In this dissertation,100MW and 150MW air-eooled generator sets are taken as the research objects.Since the classical ventilation design cannot satisfy the refined design,the finite element calculation methods of rotor indirect coupling and direct coupling are proposed.Both calculation methods meet the requirements of engineering design.The rotor direct coupling calculation method is more accurate.Because the temperature measuring data in the large generator are easy to obtain,Most of the literatures about the study of the fluid flow law in the generator are based on the measured temperature value of the generator indirectly as the judgment for the accuracy of calculation.However,the most direct way to verify the internal fluid distribution is to obtain the fluid flow and pressure test value.The velocity distribution of 100MW turbo-generator stator ventilation duct was measured experimentally.It was found that the wind speed in several ventilation ducts was significantly lower than that in other ventilation ducts.At the same time,the velocity distribution in the ventilation duct under experimental conditions is calculated,and it is found that the calculated results are the similar as the experimental results,which proves that the calculation method is correct.And then,the same calculation method is used to calculate the flow rate distribution law in the ventilation duct at different flow rates.The existence of reflux phenomenon is found,which will adversely affect the temperature rise of local stator core.The corresponding structural optimization scheme was proposed to effectively inhibit the generation of reverse reflux.Based on the CFD,the fluid distribution and loss distribution in the stator and rotor of the generator are considered completely.The distribution of stator bar,stator core and main insulation temperature in stator are calculated.The causes of air temperature rapid increase in air gap are analyzed.Finally,the temperature field distribution of the bar in short circuit test condition is calculated,and the measured values are compared to verify the correctness of the calculation.The temperature field of the main insulation i5 studied after the main insulation shelling of the air-cooled Turbo-generator stator.The temperature field after the main insulation shelling is calculated based on the finite element method.The maximum temperature drop and the temperature distribution of the stator main insulation along the circumference and the radial direction of the stator insulation are calculated.When the main insulation of the stator is unilateral shelling,the temperature drop of the main insulation of the shelling side is obviously smaller than un-shelling side.With the increase of the shelling gap,the main insulation temperature drop of the shelling side becomes smaller,and the un-shelling side becomes is larger.The maximum temperature drop of the main insulation is on un-shelling side of the upper winding after the unilateral shelling occurs;The result can provide a theory for the diagnosis of the generator when the fault occurs.