Load Optimization Control Method for Multiple Open Rack Vaporizers in Liquefied Natural Gas Station

From the operating data of open rack vaporizer (ORV), we found that: the smaller the liquefied natural gas (LNG) flow rate, the lower the seawater heat required per unit LNG. Possible reasons: When the LNG flow rate is low, the proportion of cold naturally lost during transportation to the total cold capacity becomes larger. We can reduce the seawater heat required by ORV by increasing the number of operating ORVs. As the number of ORVs in operation increases, if the calculated seawater flow rate of a single ORV is lower than the minimum film-forming flow rate, it can only be maintained at the minimum film-forming flow rate, resulting in an ineffective increase in seawater flow rate. The lowest overall seawater heat does not necessarily lead to the lowest total seawater flow rate. This paper proposes a new method for optimizing the operation of multiple ORV vaporizers in an LNG station. First, the required seawater heat is calculated based on the LNG flow rate, and then the optimal combination with the lowest total seawater flow rate is found based on the ORV constraints and environmental protection requirements. This paper gives a case study of an LNG station with 4 ORVs operating in parallel.