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- Measurement of NOx Concentration
Measurement of NOx Concentration
| Industry | : Power |
| Product | : Infrared Gas Analyzer (SG700) |
Introduction
NOx Measurements in Denitration of Gas Engine Exhaust
Cogeneration systems that improve overall energy utilization
by simultaneously generating electricity and heat from a single
fuel source have been in the news a lot recently. Distributed
generation equipment, a type of cogeneration system, is driven
by a gas or diesel engine. Advantages of the gas engine, which
is widely used, include high thermal efficiency and secure fuel
supply. However, the exhaust is likely to include pollutants
such as nitrogen oxides (NOx) because of the high combustion
temperature in such engines. To prevent air pollution, it is critical
to control the exhaust gases.
NOx removal equipment based on an ammonia injection
process is commonly used to reduce NOx emissions. Optimum
control of ammonia injection is achieved by NOx measurement,
thereby reducing the cost of running such equipment. The highly
sensitive and reliable SG700 stack gas analyzer is most suitable
for the continuous measurement of NOx concentrations.
Expected Benefits
| - | Accurately measures NOx concentrations in gas engine exhaust |
| - | Reduces cost of operating NOx removal equipment |
| - | Minimizes need for equipment replacement |
Process Overview
NOx in gas engine exhaust can be reduced by decomposition with a catalyst or the use of a reducing agent such as ammonia. Since
solid catalysts have a short life, a more stable wet denitration process using liquid ammonia is generally employed. By mixing exhaust
gases with ammonia, NOx is converted to harmless nitrogen and water. The reaction is expressed as follows:
NOx + NH3 + (catalyst) --> N2 + H2O
The running cost of a liquid ammonia process is high, necessitating NOx measurements before and after the operation of NOx removal
equipment to control the amount of ammonia that is injected.
Solution Details
| Measurement system | |
| Probes: | When sample temperature is from acid dew point (150°C) to 700 °C: Type M1E Filter Probe; P/N K9219ED |
| Stack gas analyzer (NOx, O2): | Model: SG700-B-1CJNNNNNN-1☐☐☐☐....... |
| External drain separator: | P/N K9641EA |
| Sampling tube: | SG8SAP |
| Standard gas cylinders | Zero gas cylinder for O2 calibration (Required to be purchased locally) Span gas cylinder for NOx calibration (Required to be purchased locally) Air for O2 span and NOx zero calibration |
| Utilities | |
| Power supply: | 100/110/115/220/240 V AC, 50/60 Hz |
| Power consumption: | 600 to 1000 VA, depending on specifications |
| Notes | ||||||||
| An external separator should be used when: | ||||||||
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| Gas engine exhaust has a high moisture content. Care must be exercised not to allow drain pockets to form in the sampling tube. Care must also be taken to prevent excessive engine vibration. |
| • | In Japan, NOx emission regulations apply to gas engines as well as gas turbines and diesel engines and NOx-O2 measurement of exhaust is obligatory. |
| • | Since the gas fuel has little sulfur content, sulfur dioxide (SO2) is not present in the gas engine exhaust. |
Field Data
Process Conditions
| Measurement Point | ||
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| Measuring Range | ||
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| Benefits | ||
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