UOP Advanced Mercury Removal Technologies Tech Paper
UOP Advanced Mercury Removal Technologies Tech Paper
UOP Advanced Mercury Removal Technologies Tech Paper
SpecialRepoRt
In supplying purification solutions to the gas-processing industry, a number of approaches for mercury removal have been developed. Several process options using both regenerable and nonregenerable fixed-bed technologies are available. The protection of
aluminum heat exchangers can be accomplished by using a layer
of silver-containing molecular sieve inside the dehydration vessels.
The active silver forms an amalgam with any mercury present,
and its zeolitic substrate adsorbs moisture in the treated gas. This
approach offers flexibility in being regenerable, as the mercurycontaining gas is bypassed around any cryogenic equipment. If
necessary, condensed mercury can be collected, and the mercuryentrained gas treated with a small non-regenerable guard bed.
Another approach uses non-regenerative metal sulfides to
remove mercury from the raw gas upstream of the dryers and the
amine unit. Utilizing larger vessels, this approach also protects
the brazed-aluminum heat exchanger and ensures less mercury
contamination in and around the process plant.
A comparison of mercury-removal processes will be described
via several case histories that examine regenerative zeolitic and
non-regenerable metal sulfide-based solutions. Plant-specific
drivers for each approach will be discussed as well as the efficacy
for each technology.
contaminants of concern. Process systems designed to
purify hydrocarbon feed streams are commonly used in the natural gas (NG) industry and are becoming increasingly important. Historically, NG components such as sulfur, carbon dioxide
(CO2) and water (H2O) have been effectively removed by using
regenerable molecular sieves, non-regenerable fixed-bed absorbents, membrane systems and amines.
Mercury is a naturally occurring element found in small but
measurable concentrations in many oil and gas fields. This metal
8214.indd 1
1/20/10 10:11 AM
SpecialRepoRt
A recent variation in using either a silver-impregnated molecular sieve or a non-regenerable absorbent now combines the two
approaches. Installing a small vessel of non-regenerable absorbent
to treat desorbed mercury from the molecular sieve unit permanently removes any mercury from the sales gas. Recognizing and
understanding the drivers involved in the decision-making process
when selecting the best available technology is the key and often
varies markedly from plant to plant.
Analysis and typical global levels. Table 1 lists the results
North Africa
1100
North America
120
South America
1105
Southeast Asia
102,000
Middle East
110
Europe
150
8214.indd 2
1/20/10 10:11 AM
Raw
natural gas
Raw
natural gas
Feed-gas
separator
Non-regenerable
absorbent
Molecular
sieves
CO2 removal
Fig. 1
Advanced
adsorbent
CO2 removal
Dryers
Molecular
sieves
Feed-gas
separator
Fig. 2
Dryers
8214.indd 3
1/20/10 10:11 AM
Non-regenerable
absorbent
Raw
natural gas
Molecular
sieves
Feed-gas
separator
Advanced
adsorbent
CO2 removal
Fig. 3
Dryers
Fig. 4
Natural gas
265
48
Operating temperature, C
18
50200
< 0.01
8214.indd 4
1/20/10 10:11 AM
SpecialRepoRt
Gas treated
Gas flowrate to mol sieve vessels, MMscfd
Absorbent operating temperature, C
Absorbent operating pressure, kg/cm2
Raw gas Hg concentration to HgSIV 1, ng/Nm3
Regeneration gas Hg concentration to absorbent, ng/Nm3
Effluent Hg concentration from absorbent, ng/Nm3
MRU inlet
MRU outlet
0
Fig. 5
5
6
7
Months online
10
11
12
Natural gas
750
3040
70
Up to 800
Up to 2,000
< 10
2
3
4
6
7
8
lITeRATURe CITed
Willhelm, M. S., Risk analysis for Operation of Aluminium Heat Exchangers
Contaminated by Mercury, Annual AICHE Conference, April 2008, New
Orleans.
Lund, D.L., Causes and remedies for mercury exposure to aluminum coldboxes, 75th Annual GPA Convention, March 1113, 1996, Denver.
AIChE Paper Jointly authored by UOP and Equistar, Mercury removal from
cracked gas a liquid streams, Ethylene producers conference, April 2004.
Biscan, D. A., R. S. Gebhard, T. M., Matviya, Impact of process conditions on mercury removal from natural gas using activated carbon, 8th
International Conference on Liquefied Natural Gas, 1986.
Edmonds, B., R. A. S. Moorwood and R. Szcepanski, Mercury partioning
In natural gases and condensates,GPA European Chapter Meeting, London,
March 1996.
2009 TLVs and BEIs ACGIH.
Private correspondence with Begemann Milieutechniek B.V. Mercury waste
reclaimers.
Corvini, Stiltner, Clark, Mercury removal from natural gas and liquid
streams.
Neil Eckersley is the UOP business manager for Aluminas and Specialties responsible for its complete portfolio of alumina-based solutions including mercury and
sulfur removal products. He graduated from Sheffield Hallam University in the United
Kingdom with a BS degree in chemistry and has worked in the areas of Research,
Technical Service, Sales and Product Management.
Article copyright 2010 by Gulf Publishing Company. All rights reserved. Printed in U.S.A.
Not to be distributed in electronic or printed form, or posted on a website, without express written permission of copyright holder.
8214.indd 5
1/20/10 10:11 AM
8214.indd 6
1/20/10 10:11 AM