Adsorption Solutions, L.L.C.

Mercury Removal

Mercury can be removed from gas streams, from liquid hydrocarbon streams, and from water. In some cases mercury can even be recovered. In the hydrocarbon process industries usually the mercury levels are low and pose no environmental concerns. However, even low ppb levels of mercury can damage aluminum heat exchangers and deactivate catalyst.

Mercury is removed from process streams using fixed bed adsorbers. There are two types of adsorbers used: non-regenerative, and regenerative.

In non-regenerative mercury removal the process fluid flows continuously through the bed for a number of years. When the mercury is detected in the effluent, the adsorbent needs to be replaced. A number of different mercury removal adsorbents are available with various tolerances to operating temperature, liquid hydrocarbons, and liquid water. This operation is simple since no regeneration equipment and special valving is required. The mercury stays on the adsorbent and does not leave the adsorber. The downside is that this method does add to the pressure drop on the process stream. Also, the eventual disposal of the used adsorbent can be expensive since the adsorbent not only picks up the mercury, but it will often contain other hazardous material such as benzene and other hydrocarbons.

The regenerative mercury removal is usually practiced simultaneously with drying or some other contaminant removal process. The mercury is adsorbed during the purification step, and then regenerated off the adsorbent and the mercury leaves the adsorber with the spent regeneration gas. Depending on the amount of mercury present in the feed fluid, and on the conditions in the spent regeneration gas knock out separator, much of the mercury can be collected and recovered as liquid mercury.

The plus side of this method is that there is no additional investment for the adsorbers and there is no additional pressure drop introduced on the process stream. The down side is that there will be mercury left in the gas from the knock out separator. However, since this stream is much smaller than the process stream and contains only the un-recovered mercury, it can easily be treated with a small bed of non-regenerated mercury removal adsorbent.

We can design the mercury removal system that fits your needs.

Mercury Analytical. Because we are dealing with concentrations in the ppb to ppt levels, mercury analysis is more difficult than the typical analyses done in a refinery or in a gas plant. A number of analyzers are available for low level mercury analysis which utilize a variety of detection mechanisms such as cold vapor atomic absorbance, electron fluorescence, atomic emissions, or electrical resistance. Generally they all work fine in the laboratory under controlled conditions. However, to get accurate in-plant measurements special care must be used in the design of sampling points, the sampling system, and the sampling procedures. Unless the analyzer is broken it will give a response. To avoid generating false information, great care must be taken to insure that the analyzer result corresponds to the process fluid composition.

We have in-plant mercury analytical experience and can assist you with your analytical needs.

Key Mercury Removal Publications

Use of Jerome 431X Mercury Analyzer

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