Cr – series FTIR Gas AnalysersEngine Emissions Monitoring System

Antti HeikkiläGASMET Technologies

OVERVIEWCR-series FTIR Gas Analysers

Cr-series

Four models• CR1000

– 1cm, 4 cm, 10 cm path length, peltier cooled detector• CR2000

– 40 cm or 200 cm path length, LN2 detector

• CR2000 s– 40 cm or 200 cm path length, LN2 detector– 14 Hz scan rate, RS-422 COM port (921.6 kb/s)

• CR4000– 980 cm path length, LN2 detector

Cr-series

Typical applications• CR1000

– Catalyst research, process optimization studies• CR2000 and CR2000 s

– Engine emissions monitoring, other R&D applications calling for rapid instrument response and short measurement time (500 to 1000 ms cycle)

• CR4000– Trace gas analysis in laboratory applications or e.g. Gas

manufacturers’ quality assurance monitoring

Cr series vs Cx and Dx series • Cr-series enclosure

– Larger enclosure, more space for different detector and sample cell arrangements, including some not available in other series

– Will be replaced by Cx-style 19” enclosure in the future (all detectors and cells)– CR2000 s is already built in a 19” rack mounted unit

• LN2 detectors– Wide spectral range (4200 ... 700 cm-1, potentially 7000 ... 700)– Better SNR at all wavelengths, especially in the low wavenumber end– Good SNR means that same detection limits are achievable with less scans / shorter

measurement

• ZnSe optics– Antireflection coated Zinc Selenide windows are transparent down to 650 cm -1 and have

better transmission than BaF2 windows

– Some gases are reactive towards ZnSe (CR1000 !) and BaF2 or Silicon windows may be used if sample matrix requires it

CR100m• The 100 meter instrument has been discontinued• There are parts available for building one if necessary• While the 100 meter cell has very low detection limits, it suffers from

long response time• Large internal surface of anodized aluminum (≈ 1 m2) and a large gas

volume (30 liter) require long flush times up to 45 minutes• Due to long optical path length, absorption of atmospheric levels of

H2O are significant (comparable to 30% in CX4000 / DX 4000)• It has been difficult to find an application where the drawbacks could

be accepted• Applications calling for detection limits < 100 ppb are often not good

FTIR applications (other technologies with high sensitivity exist)

Engine emission system

• CR2000 s analyser• Gasmet computer with RS422 COM port• Special sampling system incorporating a high

flow rate pump (KNF N0100ST.16E)• Fine particle filter in probe, no particle filter in

pump unit• Heated lines 5 m + 1 m• Nominal flow rate 100 lpm

Engine emission system

• 600 mm × 600 mm footprint• Same cabinet as CEMS II, only shorter• Wheels available• Old sampling system shown• New sampling system will be masked

behind a front plate• Liquid nitrogen filled from top of

cabinet

Engine emission system

Response time test with NO

• NO injected at probe (105.0 s)

• NO concentration reaches 10% of target at 105.92 s

• NO concetration reaches 90% of target at 106.60 s

• Lead time = 0.92 s• Rise time (t10-90) = 0.68 s• Overall response time is

1.60 s

NO injected t10-90

Comparison with Horiba MEXA• Comparison of

Gasmet CR2000s and Horiba Mexa (Chemiuminescence) NOx analysers

• Overall timing of peaks and average concentration level between peaks is in fair agreement

Comparison with Horiba MEXA• FTIR records higher

and somewhat narrower peaks – better response time than the Horiba CLD analyser which is the industry standard for NOx measurement at the moment. Here is a close-up of a short period where the peak width is well visible:

Calcmet v11 Pro and Engine emission monitoring system• Calcmet Pro is required for fast measurement mode (921

kb/s data transfer over RS-422 cable)• Calcmet Pro supports AK protocol for full integration with

engine and chassis dynamometer instrumentation– AK protocol is a Modbus-like serial bus protocol, where a master

sends commands (ASCII strings) to slave devices– Commands include measurement result query, sampling system

control, start/stop measurement and forced measurement of zero calibration and zero / span checks

Fast Measurement Mode• Number of scans can be chosen

freely (2 – 14, even number)• Measurement interval is the time

between starts of consequtive measurements

• Interval consists of: – Scanning interferogram– Computing spectrum– Transferring data– Analysis– Writing to disk and outputs– Waiting for interval to roll over

AK protocol in Calcmet

• Choose AK option in Configration > Serial Output menu

• Enable remote control• Define output channels in Edit > Analysis

Settings > AK protocol menu• Up to 32 channels can be defined

Typical AK request and replyByte Field Name Example

1 STX 2

2 Delimiter ASCII ’_’

3 Function code letter 1 ASCII ‘S’

4 Function code letter 2 ASCII ‘T’

5 Function code letter 3 ASCII ‘B’

6 Function code letter 4 ASCII ‘Y’

7 Delimiter ASCII ’Space’

8 Device ID prefix ASCII ‘K’

9 Device ID ASCII ‘0’

10 ETX 3

Byte Field Name Example

1 STX 2

2 Delimiter ASCII ’_’

3 Function code letter 1 ASCII ‘S’

4 Function code letter 2 ASCII ‘T’

5 Function code letter 3 ASCII ‘B’

6 Function code letter 4 ASCII ‘Y’

7 Delimiter ASCII ’Space’

8 Error Status ASCII ‘0 - 9’

10 ETX 3

Command contains a function code (STBY = go to standby mode) and device ID.Device with corresponding ID echoes function code and adds an error status to message

AK commands in CalcmetCommand Description

STBY K0 Sets the unit in stanby mode. Cancels any measurement in progress.

SREM K0 Sets the system in remote mode.

SENT K0 L1 x Sets the next sample line to be measured to line x.

SUGR K0 Starts zero calibration.

SINT K0 Starts a continuous fast measurement.

SMGA K0 Starts a continuous normal measurement cycle.

SSPL K0 x Performs an instrument air flush of the sampling system. The time x is optional.

SRUC K0 x Performs a filter backflush. The time x is optional.

SNGA K0 Performs a zero check.

SEGA K0 Performs a span check sequence for all span gases defined in the application.

SBIB K0 x Loads a new application library. Parameter x denotes the library name.

Command DescriptionASTZ K0 Inquires device status.

ASTF K0 Inquires current error codes. Reply dependent on customer, see next slide.

AKFG K0 Inquire current configured component names.

EKFG K0 x1 x2 x3 ...

Configure message components. The components names need to match the names given to the components in the library. Names may not contain spaces.

AIKO K0 Inquire current component concentrations.

AANG K0

Inquire the last zero check results. The reply format is Ma x y z, where ‘a’ denotesthe number of the span gas line, ‘x’ the measured concentration, ‘y’ the absolute difference between the target and the result concentration and ‘z’ the error in percentage of measuring range.

AAEG K0 Inquire the last span check results. The reply format is as above in zero check results.

AENT K0 Inquire the current sample line.

AK error codes in CalcmetCommand Description1 Low background. Activated when background is not within background signal

limits. 2 Humidity. Activated when the background water alarm is activated. 3 (C) Low gas pressure. Activated when the sample cell pressure is below the low

alarm limit.4 (C) High gas pressure. Activated when the sample cell pressure is above the high

alarm limit. 5 Cell temperature low. Activated when the sample cell temperature is below the

low alarm limit. 6 (C) Cell temperature high. Activated when the sample cell temperature is above the

high alarm limit. 7 (C) Heated line temperature low.

8 (C) Heated line temperature high.

9 (C) Heated filter temperature alarm.

C denotes custom code, not available in standard configuration of engine emission monitoring system. These were originally created for MAN Diesel.

CR2000 in on-road emission monitoring

CR2000 and PSS

• Portable sampling system used as space was critical

• Other instruments for ambient air monitoring and particular matter analysis

• Combined data from tailpipe and ambient air compared against location and traffic density