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MI is the company, that offers the first
commercially available continuous emission monitor (CEM) for
stack gases, the Stack Monitor SM-3, with a new operating
principle, based on the thermo-catalytic method. Wet chemical
sample gas treatment using reagents and bubblers is avoided!
The SM-3 is approved by German TÜV. |
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| Fields of application |
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The SM-3 Mercury Stack Gas Monitor is used for
continuous monitoring of mercury in stack gas. Bound
forms of mercury like HgCl2, HgO, HgS and particulate
mercury are detected as well as elemental mercury.
- Municipal Waste Incinerators
- Sewage Sludge Incinerators
- Hazardous Waste Incinerators
- Cement Production
- Coal Fired Power Plants
- Thermal Soil Resanitation Plants
- Wood Combustors Using Recycled Wood
- Metal Recycling Furnaces
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| Operating principle |
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A sample gas stream is taken from the duct through a
heated sampling system. The gas is drawn through a
high-temperature particulate filter and subsequently
enters the reduction unit. In this part of the analyzer
a thermo-catalytic reduction of ionic and bound mercury
is performed. Elemental mercury vapor is formed as a
result of this transformation process. The gas is then
dried in a maintenance-free peltier cooler and fed to
the mercury detector where the mercury concentration is
measured with the so called "cold vapor atomic
absorption spectroscopy (CVAAS)" method. The high
surface temperature of the gas entry filter guarantees
that mercury is thermally completely desorbed from
particles and thus also detected.
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| Design features |
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All surfaces coming into contact with the sample gas
are heated to temperatures >180¡C to prevent any
adsorptional loss of mercury . The sample line is made
of perfluoralkoxy (PFA), a material which shows
extremely weak interaction with mercury vapor. Sampling
and reduction are performed at temperatures far above
the dew point. Therefore no condensate is formed before
all mercury is in elemental state. This minimizes signal
noise and avoids nonspecific peaks.
The SM-3 avoids to use any gold collector for mercury
preconcentration thus giving a very fast response and
providing results continuously and in real-time.
Possible problems connected with "poisoning" of the gold
surface are thus eliminated.
The straightforward analysis avoiding wet-chemical
sample treatment and avoiding a gold trap ensures high
reliability and low maintenance. |
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| Easy to operate |
| The SM-3 is operated via a waterproof
membrane keypad. All inputs required are selected in a
readily understandable menu shown on the graphical
display. It is also possible to initiate functions like
zero adjustment and calibration check from an external
computer. |
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| Low maintenance and low costs of
ownership |
| Thanks to the new thermo-catalytic sample
treatment method no reagents are required. Compared to
first generation instruments employing wet chemical
sample preparation methods, the SM-3 features clearly
increased reliability and requires only minimum
maintenance. This results in particularly low cost of
ownership and maximum availability. |
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| UV-Photometer |
| Quantitative determination of the mercury
concentration is performed in a UV-photometer with an
electrodeless low-pressure mercury lamp. This lamp is
controlled using the reference-beam-method which ensures
a highly stable baseline. |
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| Automatic zero adjustment |
| The zero line of the SM-3 is checked and
adjusted automatically after a preset period of time. A
magnetic valve stops the sample gas stream and switches
over to zero air which has been cleaned in a carbon
filter. Automatic zero adjustment is performed every
hour and requires 30 seconds. |
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| Automatic self-cleaning
filter |
| To prevent the instrument from being
plugged up by dust-particles, the SM-3 has a
self-cleaning filter system which is operated by
compressed air. The cleaning function is automatically
activated every hour and is a matter of seconds |
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| Sampling system |
| The sample gas is extracted with a
stainless steel probe and conducted through a heated
tube to the analyzer. The entire sample line is made of
perfluoralkoxy (PFA), a material guaranteeing a minimal
memory effect. The dimensions of the sampling system
mounting flange are customized (for example DN 80/PN 6
or ANSI 3"/ 150 labs). |
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| The importance of continuous
mercury emission monitoring |
| Monitoring of mercury emissions from
stack has become a global issue. More strict regulations
by authorities as well as the public claim for a
complete surveillance of incinerators have caused an
increasing interest in continuous emission monitors
(CEMs) for mercury. For the potential user of such
systems it is important to find a reliable and economic
solution. First generation CEMs for mercury were based
on the automation of known laboratory methods. This
resulted in high maintenance costs, unreliable
operation, oversized and heavy construction and last but
not least a high price. |
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| A new analytical solution: the
SM-3 |
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The operating principle of the
SM-3 is based on a completely new technique.
Cracking and reduction of bound and ionic mercury
contained in stack gas is performed applying the
thermo-catalytic method. Wet chemical sample gas
treatment using reagents and bubblers is avoided.
Maintenance and servicing of the SM-3 are
therefore extremely easy. Purchasing costs for
purchase and costs of ownership are comparatively
low.
As the SM-3 is a compact-sized
and low-weight device, it may also be used for
mobile applications. Installation is easy and done
in a short time.
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| SM-3 Technical
Specifications |
| Measuring
component: |
total mercury
Hg(tot) |
| Measuring
principle: |
UV-Absorption after
thermo-catalytic sample gas treatment |
| Measuring
range: |
0 - 45; 0-75; 0-500
µg/m³ (others upon request) |
| Detection
limit: |
< 1% of measuring
range |
| Response time
T90: |
< 60
seconds |
| Measurement cycle
time: |
none, continuous
measurement without time gaps |
| Zero drift: |
< 1 % of range, auto
zero |
| Air supply: |
oilless compressed air,
approx. 2.0 bar (approx. 25 psi) |
| Operating
temperature: |
5 - 40 °C |
| Signal
outputs: |
4-20 mA (max. load 500
Ohms) digital status outputs (relais
contacts) |
| Power Supply: |
230 VAC/ 50-60 Hz
(optional 115 VAC / 50-60Hz) |
| Power
consumption: |
max. 1000 VA
(analyzer) max. 150 VA/m (sample
line) |
| Dimensions: |
550 x 1000 x 700 mm
(WxHxD) |
| Weight: |
approx. 50
kg | | |
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Hg-CEM Questionnaire for CDFs
1. SETUP
1.1 : What are the space requirements ?

1.2 : What are utility
requirements?
230 VAC, ca. 750 VA for analyzer, ca. 120 VA per meter for heated
sample line
compressed air, oil-free, ca. 10 l/hour
1.3 : What range of ambient conditions can
the CEM tolerate?
+ 5°C to + 40 °C
1.4: Are there any other requirements for
unit location or setup?
sample line as short as possible, standard length 10-12 m,
maximum 20-30 m
2. MERCURY ANALYSIS METHOD
2.1: Mercury speciation or total mercury?
Total mercury
2.2: Is particulate-bound mercury
detected? By what method?
Yes, thermal desorption of particulate Hg at ca. 400 °C
2.3: Do false positives
occur?
Yes, if SO2 greater than 100 mg/m³. Can be corrected very
exactly if signal/concentration of SO2 is available
Yes, if benzene is > 1 mg/m³
2.4: Would mercury spikes beyond the
instrument span overload the CEM and require downtime to
reset?
depending on the peak concentration and duration it may take some
minutes to some hours until excess Hg is purged out
2.5: What are the cycle times? Please give
time for each step.
No cycle time, real continuous measurement
2.6 : Are multiple instrument spans
available in the same CEM? Is there automatic switching of
spans?
Yes: 3 spans. Manual switching. Automatic as an option.
3. CALIBRATION
3.1: Describe the calibration
method.
Calibration is performed by feeding the instrument with humid (!
Important!) ionic mercury (Hg-II) calibration gas. We use the
"HOVACAL" calibrator which has been approved. Official calibration
is performed by comparison of the instrument´s reading with results
from manual reference analyses.
Automatic calibration is possible with a permeation device for
elemental Hg attached to the analyzer.
3.2: What calibration frequency is
recommended?
Calibration check every 6 months is recommended.
3.3: What percentage of time would the CEM
be offline for routine calibration?
Manual routine calibration time requirement: ca. 30 min to 1
hour.
3.4: What mercury calibration gases are
required?
Cf. 3.1
4. SIGNAL OUTPUT
4.1: What signal outputs (including Hg
concentration, CEM operational status, calibration status, etc.) are
available?
Measuring signal 4-20 mA, status outputs for
"zeroing/calibration", "maintenance", "malfunction"
4.2:What is the form of the signal
outputs?
4-20 mA, potential-free relais contacts
5. SAMPLE EXTRACTION SYSTEM
5.1: What type of sample extraction system
is used?
heated sample line with passive heated probe tip
5.2: What is the maximum recommended
sample line length?
up to 30 meters, optimum <12 m
5.3 :What is the sample line material of
construction?
PFA tubing, from tip to thermo-catalytic reactor intake
fitting
5.4: What is the acceptable temperature
range for the sampling line?
ambient temp range from –20 °C to + 50 °C
Heating temp 170-190 °C
5.5: What type of filtration is
used?
Heated glass filter (400 °C)
5.6 : Would it be possible to analyze gas
samples drawn from two different process locations? If so, what
would be the switching interval? Would there be difficulties with
cross-contamination?
Absolutely not recommended.
6. REGULATORY REQUIREMENT
6.2: Is the CEM
TUV-certified?
Yes, the SM-3 has been TÜV certified and approved in 1999 as the
first instrument working on thermocatalytic principle.
6.3 : Is the CEM MCERTS
certified?
Manufacturing according to ISO 9000
6.5: Were the interference response tests
conducted with individual interference gases or with a mixture of
gases?
With individual gases. If other tests have been carried out is
not known
7 TESTING
7.2: What independent performance testing
has been conducted to date? Please provide results.
More than 40 installations. For each instrument functional tests
have been carried out. A variety of other tests (for example
comparative tests of instruments from different manufacturers at
cement kilns by the German Research Institute of the Cement
Industry) have been carried out too.
7.3: What testing is planned for the
future?
SM-3 testing and evaluation will be conducted
at a proprietary US site from August –October 2002
8. OPERATION
8.1: What routine maintenance (type and
time is required)?
Discharge of condensate every 4-8 weeks. Routine maintenance
every 6 months (requiring ca. 3-4 hours of work). Cleaning tubing +
reactor, replacement of peristaltic pump tubing, cleaning of glass
filter.
8.2: What degree of skill and training is
required of the CEM operator? Is training provided
onsite?
Averagely skilled personnel who is used to maintain other
analyzers. Training can be provided during start-up (1 day).
Generally the analyzer is easy to understand and to maintain. No
complicated adjustments.
8.3: How much operator time is
required?
Operator time: 0.5 … 5 hours/month
8.4: Is there failure rate or availability
data for the CEM?
Availability (run time of the analyzer) during standard
operation: 95- 100 %. During approval test: one instrument 98,6 %,
second instrument 99,2 %)
9 GAS CONDITIONS
- The following parameters represent the
range of gas conditions expected in the streams to be sampled.
Please indicate any values which are a potential problem, and
any parameters which have not been tested on the
CEM.
N2 35-75%
O2 3-10%
CO2 3-10%
H2O 10-55%
CO 0-76 ppmv
NOx 0-350 ppmv
SOx 0-350 ppmv
HCL 0-10 ppmv
CL2 0-10 ppmv
HF 0-10 ppmv
TOC 0-5 ppmv as propane
P2O5 0-5 ppmv
PM 0-300 ppmw
HG° 0-150 ug/m3 (total
Hg)
Differential Pressure –55 in w.c.
Relative Humidity 10-50%
Temperature 150-300 F
Degrees Above Saturation 25-125 F
There is no major problem visible, but we don’t know the behavior
if all these components are present.
10 REAGENTS AND SECONDARY WASTE
10.1: What types and quantities of
chemical reagents and other expendable materials are
required?
None used
10.2: What types and quantities of
secondary waste are generated by the CEM?
Stack gas condensate. Amount dependent on humidity of sample, ca.
0.2-0.51/d
INDUSTRIAL EXPERIENCE AND
REFERENCES
- List industrial applications to date.
The SM-3 has been installed at municipal
waste incinerators, industrial waste incinerators, sewage sludge
incinerators, waste pyrolysis plants, paper industry waste
incinerators, coal fired power plants and cement
kilns.
WARRANTY AND TECHNICAL SUPPORT
- What type of warranty and technical
support are provided with the CEMS?
6 Month Warranty
- Is technical support provided in the
USA?
Yes
- Are repair service provided in the
USA?
Yes
COST
What are the equipment and estimated
installed cost for the CEM?
$60,000.00
What is the estimated operating cost?
Minimal
FUTURE DEVELOPMENT
What are the plans for future development of the
CEM?
The SM-4 is under development
Is a new model planned? If so, when?
The SM-4 will be under testing possibly by the end of
2002.
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