液化天然气动力船供气系统动态模拟

本文以液化天然气(LNG)动力船供气系统的工作流程为原型，讨论发动机在工况变化时如何设置控制方案，以达到更好的温度控制效果，满足双燃料发动机的工作需求。使用Aspen HYSYS流程模拟软件对该工作流程进行模拟，研究动态模拟时系统的运行情况。针对供气时的工况变化，改变液化天然气的流量，同时供气温度需要稳定在一定范围内，提出两种维持供气温度相对稳定的调节方案：改变热源的供热量或调节加热介质（水乙二醇）的流量，在HYSYS中分别进行动态模拟。改变热水流量时，输气温度可以控制在20℃-32℃；改变水乙二醇流量时，输气温度控制在22℃-28℃。两种调控方式结合的综合方案中，天然气温度也较好稳定在22℃-28℃之间，并且不需要引入其他外加冷源，响应较快，最适合应用于实际系统中。

DYNAMIC SIMULATION OF GAS SUPPLY SYSTEM FOR LNG-FIRED SHIP

Based on the working process of the gas supply system of the LNG-powered ship, this paper discusses how to set up the control scheme when the working condition of the engine changes, so as to achieve better temperature control and meet the working requirements of the dual-fuel engine. With Aspen HYSYS process simulation software to simulate the working process dynamically, the operation of the system when the working condition changes is studied. In response to changes in operating conditions during gas supply, the flow rate of LNG is changed and the gas temperature needs to be stabilized within a certain range. Therefore, two adjustment schemes for maintaining a relatively stable gas supply temperature are proposed: changing the heat from the heat source or adjusting the flow rate of the heating medium (water glycol). Two schemes are both simulated in HYSYS. When changing the flow rate of hot water, the gas supply temperature can be controlled between 20 °C and 32 °C. When changing the water glycol flow rate, the gas supply temperature is controlled between 22 °C and 28 °C. With the combination of the two adjustment schemes, the temperature of natural gas can be maintained stable between 22 °C and 28 °C, there is no need to introduce other external cooling sources, and the response is fast, so the combined scheme is most suitable for the practical systems.