不同工况下开架式气化器最小海水流量计算

摘要

由于液化天然气(LNG)流量、压力、温度、组分和海水温度的不同,开架式气化器(ORV)所需的海水流量也不一样,普遍产生能耗过剩现象.为了确定所需最小海水流量:以ORV性能曲线为基础,确定其机械限定LNG流量,并通过1stOpt软件采用多元非线性拟合找到特定条件时,不同LNG流量、压力和海水温度下所需最小海水流量的函数式;由BWRS方程计算特定条件及实际参数下ORV入口LNG、出口天然气(NG)的焓值,再由能量守恒原则得到实际所需最小海水流量;通过计算机编程设计出计算软件.为了验证计算精度,通过性能曲线数据、Apsen_Plus软件及能量守恒式计算出实际工况对应的理论最小海水流量;将理论海水流量与软件计算值对比求出相对误差.结果证明:最大相对误差小于3％,能较好地计算所需最小海水流量,为ORV优化、节能运行,海水泵选型、变频提供了一定的理论参考.%Seawater flow requirement of open rack vaporizer (ORV) is different because of the difference among liquefied natural gas (LNG) flow,pressure,temperature,component and seawater temperature actually.Excess energy is consumed in current operation model generally.To determine required minimum seawater flow,mechanical limited LNG flow is determined based on ORV performance curves and through 1stOpt software,using multi variate nonlinear fitting finds the function that different LNG flow,pressure and seawater temperature correspond to the minimum seawater flow under specific conditions.BWRS function is adopted to calculate the enthalpy of ORV inlet LNG and outlet natural gas(NG) in specific conditions and actual parameters.And then,actual required minimum seawater flow can be obtained by the principle of conservation of energy.Using computer programming,calculation software is designed.To verify the calculating accuracy of calculation software,theoretical minimum seawater flow corresponding to actual process is worked out by the data of performance curves,Apsen_Plus software and conservation of energy formula.Relative error is obtained through comparing theoretical minimum seawater flow and software calculated value.The results prove that the maximum relative error is less than 3％.The required minimum seawater flow can be better calculated with the software.A theoretical reference for ORV optimization,energy-saving operation seawater pump selection and frequency conversion are provided.