Design Of Automatic Control System For Sulfur Recovery In Natural Gas Purification Plants

Along with the great development of global sour natural gas, Sulfur Recovery from acid gas has become an essential part of natural gas processing. Sulfur Recovery is a process which oxides H2S in acid gas coming from the desulfurization process by air as the oxidant and produce sulfur. The core of Sulfur Recovery unit is to improve the sulfur recovery rate, which on the one hand increase sulfur production, on the other hand reduce the emission of SO2 thus causing less pollution. On the premise of safe and stable operation, increasing sulfur recovery rate not only productive but also environmental friendly by the meaning of social and economy.In this paper, a certain Sulfur Recovery control system for a 126T/d natural gas conditioning plant gasification was researched and designed. In the whole control system of Sulfur Recovery the most important control loops are:acid gas control system, air control system and main combustor's interlock protection.At first, controlled object models for each control loop was built. The controlled variables are acid gas flow, oxygenation required air flow, and main combustor temperature and so on, which have direct effect on recovery rate as the process required. According to this, control requests and control schemes were presented. Then different control schemes were compared using Simulink. During the engineering practice, Emerson DeltaV system was chosen to realize centralized management and remote control. This system was introduced and according to the main control loops, control modules were designed, as well as the operator interface.This system was designed to realize a safe and stable sulfur recovery process and can provide some technical reference to sulfur recovery control system's design.