LNG接收站高压泵入口过滤器极限压差计算及影响因素分析

Calculation of Limit Pressure Difference of High Pressure Pump Inlet Filter and Analysis of Influencing Factors in LNG Receiving Station

LNG接收站为了保证高压泵的安全运行,通常会在其入口安装过滤器,防止杂质进入泵体损坏机泵,同时会设置过滤器前后压差高报警值,作为过滤器堵塞程度及需要清理的依据。若压差高报警值设置过小,则需要频繁清理过滤器,不但导致工作量增量,而且会大大降低高压泵使用寿命;若设置过大,则会影响高压泵运行稳定,甚至造成全站停车或机泵损坏。因此根据LNG接收站实际工艺,首先以高压泵入口压力低报警值为基础进行分析,得到过滤器极限压差为125.60 kPa;其次对高压泵泵井放空气体返回至再冷凝器工艺进行分析,得到此工艺条件下过滤器极限压差为35 kPa;然后对放空气体返回至低压排净工艺进行分析,得到平衡管压力取值范围为0.677~0.680 MPa,此工艺条件下过滤器压差极限值为38 kPa。最后通过对比高压泵泵井放空气体返回至再冷凝器或低压排净管线两种工艺得到:高压泵泵井放空至再冷凝器,过滤器极限压差略小,运行影响因素多,但能耗低;高压泵泵井放空至低压排净管线,能耗相对偏高,过滤器极限压差略大,运行影响因素少。

In order to ensure the safe operation of high pressure pumps, LNG receiving stations usually install filters at the inlet to prevent impurities from entering the pump body and damaging the pump. At the same time, high alarm values of pressure difference before and after the filter are set as the basis for filter blockage diagnosis and cleaning. If the pressure difference is high and the alarm value is set too small, the filter needs to be cleaned frequently, which not only leads to workload increment, but also greatly reduces the service life of the high pressure pump;If the setting is too large, it will affect the stable operation of high pressure pump, and even cause the whole station to stop or pump damage. Therefore, according to the actual process of LNG receiving station, based on the low alarm value of the inlet pressure of the high pressure pump, and the ultimate pressure difference of the filter is 125.60 kPa. Secondly, the process of returning the air from the pump well of the high pressure pump to the condenser has been analyzed, and the ultimate pressure difference of the filter under this process condition is 35 kPa. Then, the process of discharging gas back to low-pressure drainage has been analyzed, and the value range of the balance pipe pressure is 0.677~ 0.68 MPa,and the limit value of the filter pressure difference under this process condition is 38 kPa. Finally, by comparing the two processes of high pressure pump well emptying gas returning to condenser or low pressure drainage pipeline, the results are as follows: High pressure pump well emptying to condenser, the filter limit pressure difference is slightly smaller, and there are many factors affecting operation, but the energy consumption is low;High pressure pump well emptying to low pressure drainage pipeline, the energy consumption is relatively high, the filter ultimate pressure difference is slightly larger, influencing factors of operation are less.