Development of a Fitness-for-Purpose Foam Depressant Having Corrosion Inhibitive Properties

摘要

Very severe operational problems, such as corrosion, foaming, and fouling, occurred in DGA units which remove CO_2 from sweet natural gas streams. The added silicone foam depressant decomposed and polymerized in the high temperature, alkaline DGA solutions and resulted in the severe fouling. The root cause of the foaming was considered to be the stabilization of foams by the corrosion products due to the severe corrosion of UNS S30403. So, a new project was initiated to develop a foam depressant having corrosion inhibitive properties. A silicone foam depressant having very high stability in the particular DGA units was selected and hydrophobic silica was added. Some trial products were evaluated from the viewpoint of corrosion inhibitive characteristics in addition to foam controlling and minimal tarring properties. The selected new foam depressant controlled the foaming and fouling very effectively. In addition to these, the new foam depressant controlled the progress of corrosion of UNS S30403 clad in the upper half of the regenerator shell in the DGA units. As a result, stable operations of the units became possible and the safety and economic efficiency of the units were improved.