Another reason for the popularity is probably because of its topic - syngas and gasification. Specifically, the analysis of syngas composition.
In this application, the critical gases are H2 and CO. However, most of our gasification customers want analysis O2 / CO / CO2 / CH4 / H2. We can offer this combination of gases in any range in a single analyzer.
Here’s one that we are building now to support a Fischer-Tropsch process in which H2 & CO are converted into hydrocarbons in the presence of a catalyst.
As a follow-up to Post #5 and Post #70, we have another update to offer on this topic:
Besides having a capable analyzer for this
application, it is also important to condition the sample properly before
analysis.
Hot Extraction and Filtration
Depending on the feedstock being used in
the gasifier, the sample may have a significant amount of particulate in it. It
is important to remove the particulate before condensation develops and mixes
with the particulate. A heated filter that is mounted behind the probe at the
extraction point is a good solution. A version of this filter can even be
produced for high pressure samples or for Class 1 Division 2 Hazardous Rated Areas.
Tars
Many of our customers have reported to us
that if the feedstock is comprised of woodchips or other wood-based matter,
there is a strong possibility of tar being in the sample gas. These tars may
condense out onto various surfaces. Especially of concern are the optical
surfaces of the detectors. We have had some success in removing tars by
integrating a gas cooler in a separate cabinet beside the analyzer. This
encourages the condensable tars to accumulate on a non-critical surface away
from the detectors. Ideally, the cooling assembly should be somewhat modular to
allow easy access for cleaning or replacement.
Theoretically, a chemical scrubber can also
remove the tars. But some of the solvents that might be used, isopropyl alcohol
for example, may be carried into the analyzer and provoke a response on the
infrared detector. This can be interpreted and presented by the analyzer as a falsely
high CH4 reading. So we have been cautious about IR analyses where these types
of scrubbers are installed. If the scrubbing solvent is water-soluble, a
possibility might be to integrate a water-wash system in front of the analyzer as discussed below. (We haven’t
tried this solution yet in this context, but it is an interesting idea.)
Soluble Gas Removal
On some projects where the feedstock is
municipal waste with high variability, we have noticed the presence of other
gases besides just H2, CO, & hydrocarbons. For example, there may be SO2 or
NH3 in the sample gas. These gases may be detrimental to the long-term
operation of the analyzer, so it is frequently best to eliminate these gases
from the sample. On some gasification projects, we have supplied water-wash
systems to scrub out any corrosive gases that are water-soluble.
Multiple Gasifiers or Multiple Sample
Points on a Gasifier System
Sometimes analysis of multiple points with
one analyzer is required. We have supplied an industrially-hardened version of
our auto-sequencer for some gasification projects. This system will continually
pull a sample from several sample points and send only one at a time to a
single analyzer. The auto-sequencer will cycle through the sample points
according to a user-defined schedule. Generally, the dwell time on each sample
is a few minutes.
Not sure if this post will become as popular
as the other gasification-related posts. But we will try to continue providing
updates on Nova solutions for this interesting application.
For information on these and other gas
analyzer systems, give Mike or Dave at Nova a call, or send us an e-mail.
1-800-295-3771
sales at nova-gas dot com
websales at nova-gas dot com
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