• What are the other methods to reduce feed foaming in DCU reactor, apart from the use of anti-foaming agents, increasing pressure and temperature? 




  • Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

    The foam formation in the delayed coking reactors can be caused by a series of factors like:

    1 - Feedstocks characteristics: The paraffinic feeds tends to present high foam level in the reactor than aromatic feeds once the paraffinic compounds cracking faster than aromatics compounds, creating a flow of gas through the liquids in the reactor. Another parameters of the feedstocks which can cause foam production is the presence of high sodium and solids concentration in the feed;

    2 - Sudden depressurization of the reactors: This disturb can cause an excessive velocity in the reactor, favouring the foam formation;

    3 - Inadequate heating of the feed: Some refiners can try to reduce the temperature to minimize the coking issues in the fired heaters and reduces excessively the feedstock temperature leading to the increasing of the foam in the reactors. It's necessary to make a balance between the coking of the fired heaters and foaming formation in the reactors;

    4 -  Excessive velocity in the reactors: The high velocity in the delayed coking reactors can be caused by a excessive flowrate of the feed as well as reduced pressure of the reactors;

    As described above, acting in the temperature and pressure of the reactors it's possible to minimize the foaming formation. Higher temperature and pressure tends to reduce the foaming production in delayed coking reactors, but it's necessary to consider the another aspects once the increasing of pressure and temperatura affects directly the quality of the produced coke.