透平变工况特性及控制策略研究

Study on Off-design Characteristics and Control Strategy of Turbine

文章基于Fliigel公式等理论基础,对透平变工况膨胀特性进行分析,并以某国产50 MW超高压透平变工况特性为例,对透平变工况特性参数进行具体分析论述,获得变工况时关键参数的变化规律:流量、负荷率降低时,透平各级压力均降低,但除末几级压比增大外,其他级次压比几乎不变。由于透平热降与压比成反比关系,可以得到透平除末几级外,热降均未明显变化。进而从热降与温降的关系可知级间温度变化与热降有相似的变化趋势。该趋势能够在分析透平变工况时,快速判断缸内参数变化趋势,尤其是对于低负荷时能推测低压缸的运行状态并对其排汽温度的变化产生快速响应,进而有针对性的指导透平的运行维护。本文对透平变工况时反动度的变化趋势也进行了论述。

In the process of turbine expansion,there will be a certain degree of temperature drop and pressure drop,and the expansion process is quite different when running under off-design conditions.In this paper,based on formulas and other theoretical foundations,the off-design expansion characteristics of the turbine are analyzed.Taking the off-design characteristics of a domestic50MW ultra-high pressure turbine as an example,the characteristic parameters of the turbine under off-design conditions are analyzed and discussed in detail,and the change rule of key parameters under off-design conditions is obtained:when the flow rate and load rate decrease,the pressures of all stages of the turbine decrease,but the pressure ratios of other stages are almost unchanged except for the increase of the last few stages.Because the heat drop of turbine is inversely proportional to the pressure ratio,it can be concluded that the heat drop of turbine has no obvious change except the last few stages.Furthermore,from the relationship between heat drop and temperature drop,it can be seen that the inter stage temperature change and heat drop have similar trends.This trend can quickly judge the change trend of the parameters in the cylinder when analyzing the off-design conditions of the turbine,especially produce a quick response to the change of the operating state of the low-pressure cylinder and the exhaust temperature of the low-pressure cylinder at low load,and then guide the operation and maintenance of the turbine pertinently.In this paper,the changing trend of reaction degree of turbine under off-design conditions is also discussed.