A safety control scheme on the production devices of large LNG plants in summers

The equipment in large LNG plants tends to suffer abnormal shutdown in the environment of high temperature in summers. In this paper, Huanggang LNG Plant of Kunlun Energy was taken as an example to deal with this problem. Based on the typical data of its main devices under the full load of one certain year at the temperature points of circulating water cooling, air cooling and natural cooling, the weight of each factor inducing the safety problems due to high temperature in summers was quantified by means of analytic hierarchy process modeling. Then, combined with the process control parameters of the LNG plant, its summer safety production scheme was prepared as follows. When the air temperature is over 40 ℃, turn on the summer spray system to strictly control the outlet temperature of circulating water, the inlet/outlet temperature of circulating water of propylene cooler, the outlet temperature of amine solution of barren-solution air cooler and the outlet temperature of acid gas of acid-gas air cooler below 32 ℃, 42 ℃, 55 ℃ and 55 ℃, respectively. After the regenerated gas flows through the regenerated-gas air cooler, its temperature is below 35 ℃. The temperature of the compressor lubricant shall be lower than 45 ℃. And the heat transfer temperature of circulating water system while entering the station is lower than 30 ℃. It is indicated that the safety production of Large LNG plants in summers shall not simply comply with the traditional work of "four defenses in summer" and the regulatory code of safety. It is necessary to take the smooth production rate as the prerequisite, combined with the demands of actual production, to quantify the qualitative problems induced by high temperature in summers into the scientific weights and formulate practical and feasible solution, so as to reduce the production risks.