Hawiyah Gas Plant New Thermal Oxidizer Combustion Control Philosophy

Hawiyah Gas Plant at Saudi Aramco recently commissioned a thermal oxidizer. The thermal oxidizer unit has two main functions that shall be achieved. The first function is to oxidize and destroy the Acid gas which has minute quantities of BTX. The BTX shall be fully destroyed at a temperature above 1800 deg F. The second main function of the unit is to provide heating media for the hot water which is used in the re-boiler of the DGA stripper in sweet gas treating unit. The hot water temperature controller has a set point of 350 Deg F thus providing constant water temperatures to the gas treat process. Hawiyah gas plant will share through this paper the internal effort to rectify the original control philosophy design problems submitted by the equipment vendor of the thermal oxidizer that fail to accommodate both functions at the same time. The paper will shed the light on all of the new innovative major advance control loops configured to achieve the appropriate hot water temperature, combustion chamber temperature in addition to the Oxygen trimming advance control. The new control scheme helps the plant to achieve more reliable system to any process changes, it helps to maintain the targeted process parameters set points and optimize the fuel consumption. Hawiyah Gas Plant will present the actual reduced figures in the fuel consumption after the modification and shows the improved in the equipment reliability. In the first part of the paper, brief description of HGP process will be shown. And In this introduction, the role and function of the Gas Treating unit 6 and its thermal oxidizer units will be discussed.