Silicone defoamer to better control hydrocarbon foam and reduce silicon content of liquid hydrocarbon products

Abstract

Crosslinked polydimethylsiloxane (PDMS) resins have now been found useful as defoamers and antifoams for hydrocarbon-containing liquids such as delayed coker feeds and pre-flash and atmospheric column feeds. These PDMS resins are crosslinked with polyalkyl silicates or siloxanes. The cross-linked PDMS resin can be used alone or with linear PDMS and is often blended with a carrier such as kerosene for easier handling. Importantly, the use of cross-linked branched PDMS resins allows a reduction in the total amount of polysiloxane to be used, which results in less silicon carryover in the coker product and less downstream catalyst poisoning.

Description

field of invention

[0001] The present invention relates to methods and compositions for controlling foaming of hydrocarbon liquids, and in one embodiment, more particularly to methods and compositions for preventing or reducing foaming of coker feedstocks using polydimethylsiloxanes, The polydimethylsiloxane reduces the silicon content of the coker liquid product. Background of the invention

[0002] Many petroleum refineries utilize delayed cokers to process residues. In delayed coking, the overhead vapor from the coking drum is sent to a fractionation column where the various fractions are separated. One of the fractions is a gasoline boiling range stream. This stream, commonly referred to as coker gasoline or coker naphtha, is generally a relatively low octane stream, unsuitable for use as an automotive fuel without upgrading. Due to the restrictions imposed on octane boosting additives for environmental reasons, it has become desirable to process coker / naphtha in octa...