Removal of Heat stable salts – A solution to Amine plant operational problems

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Courtesy of Eco-Tec Inc.

Introduction
Amine scrubbing solutions are used to remove hydrogen sulfide and carbon dioxide from gas streams in many natural gas conditioning plants and oil refineries. Two major problems represent a significant threat to an amine gas treating plant: corrosion and instability of operation, resulting in unscheduled upsets and outages. In this process, contaminant byproducts called Heat Stable Salts (HSS) are formed and gradually build up to beyond tolerable limits in the amine circulation loop. Amine plant operational problems, such as excessive foaming, corrosion and capacity reduction, are often attributed to the accumulation of amine heat stable salts. These heat stable salts lead to costly maintenance problems such as corrosions, frequent filter replacement, foaming in the absorber column, absorber tower plugging, heat exchanger fouling and a reduction in the amount of amine available for gas treatment, thereby reducing the unit’s productivity.

In order to prevent the HSS from building up beyond critical limits, amine plant operators have been making conscious attempts to control impurities, especially HSS. A number of measures have been proposed [1, 2]. The most straightforward approach is periodic amine purging, which is messy, prohibitively expensive and causes environmental problems. Other periodic amine clean-ups, either onsite or off-site, are also practiced to some extent by certain plants which have to employ large equipment for vacuum distillation, conventional ion exchange or electro-dialysis. However, this approach of periodic reclaiming is cumbersome and expensive and does not overcome the operational and corrosion problems caused by the anions.

Continuous amine reclaiming is being increasingly recognized as the most effective solution for HSS-related problems. The benefits of continuous HSS removal go beyond limiting the level of impurities in the amine loop. A continuous on-line reclaimer helps to ensure a stable and uniform gas conditioning operation where contaminant levels in the amines are prevented from building up, thus minimizing the rate of corrosion. It also ensures that amine unit operation is reliable and provides the designed gas treating efficiency.

Eco-Tec’s RecofloTM Technology Recoflo Concept
Using advanced ion exchange technology, the AmiPur, a unique and cost effective on line amine purification system was developed and introduced to the Petroleum Industry in 1998. This system employs Eco-Tec.’s Reciprocating Flow (RecofloTM) Ion Exchange technology [3,4].

Recoflo, which has been extensively used since 1973 for the recovery of metals from metal finishing wastes [5,6], is characterized by several features which differentiate it from conventional ionexchange sstems. Since 1987, the performance of these systems has been further improved by maintaining the resin inside the column under compression.

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