燃气涡轮流量计压损异常辨识实验研究

Experimental Study on Identification of Abnormal Pressure Loss of Gas Turbine Flowmeter

针对城镇燃气常用的3种规格(公称通径分别为50,80400 mm)涡轮流量计压损变化情况开展实验研究,获得涡轮流量计压损与标况流量关系式,测试分析涡轮流量计异常(叶片缺失、轴卡顿)状态的压损变化趋势。涡轮流量计的压损、标况流量成二次函数关系。对每种规格的涡轮流量计,在相同流量情况下,叶片缺失状态的压损比正常状态小,叶片缺失越多,压损越小;压损减小值随着流量增大而增大。叶片缺失造成的压损减小值较小,需结合流量计的高低频脉冲数进一步判定。对每种规格的涡轮流量计,轴卡顿状态的压损比正常状态大,卡顿程度越大,压损越大;压损增大值随着流量增大而增大,小流量(流量小于0.4倍最大流量)下的压损增大值不明显,大流量(流量大于等于0.4倍最大流量)下的压损增大值较为显著。提出建立流量计在线监测系统,通过实测压损与正常压损对比,判断流量计是否存在异常,通过实测压损比正常压损增大或减小的趋势判断流量计存在的问题种类。

An experimental study is carried out on the pressure loss change of three turbine flowmeters commonly used for urban gas(with nominal diameters of 50,80 and 100 mm respectively).The relationship between the pressure loss and the standard flow rate of turbine flowmeters is obtained,and the change trend of the pressure loss of turbine flowmeters under the abnormal conditions(blade missing and shaft jamming)is tested and analyzed.The pressure loss and the standard flow rate of the turbine flowmeters are in a quadratic function relationship.For each type of turbine flowmeter,under the same flow rate,the pressure loss in blade missing state is smaller than that in the normal state.The more the blade missing is,the smaller the pressure loss is.The reduction value of pressure loss increases with the increase of flow rate.The reduction value of pressure loss caused by blade missing is small,which needs to be further determined in combination with the number of high and low frequency pulses of flowmeters.For each specification of turbine flowmeter,the pressure loss in shaft jamming state is greater than that in normal state.The greater the degree of jamming is,the greater the pressure loss is.The increased value of pressure loss increases with the increase of flow rate.The increased value of pressure loss under small flow rate(less than 0.4 times the maximum flow rate)is not obvious,while the increased value of pressure loss under large flow rate(greater than or equal to 0.4 times the maximum flow rate)is significant.It is proposed to establish an online monitoring system for flowmeters.By comparing the measured pressure loss with the normal pressure loss,it is judged whether the flowmeter is abnormal or not.The type of problems existing in flowmeters is judged by the trend that the measured pressure loss increases or decreases compared with the normal pressure loss.