Measurement of NH3 Concentrations in Stack Flue Gas Using TDLS8000

Introduction

The ammonia (NH₃) gas is injected to remove the NOx and thus reduce the NOx concentration in the stack flue gas.

With conventional NH₃ analyzers that perform measurements indirectly, NH₃ concentrations are obtained through a sampling system. Therefore, there are problems with the maintenance and running costs of the sampling system, and time delays in measurement. The TDLS8000 Laser Analyzer is the solution to all these problems.

Expected Benefits

• Eliminates the need for sampling and reduces the maintenance and running costs of the sampling system
• High-speed response, possible to apply measurement results to control the NH₃ injection volume, and reduction and optimization of the NH₃ injection volume
• Continuous monitoring, NH₃ emission volume monitoring, and environmentally friendly
• Extends the service life of NOx removal equipment and reduces the ammonium sulfate precipitation of the air heater

Process Overview

The NH₃ gas is injected to remove the NOx and thus reduce the NOx concentration in the stack flue gas, as well as to increase the dust collection efficiency of the dust collector (ESP) and prevent erosion. Excess NH₃ injection increases the running cost and the residual NH₃ amount, resulting in the generation of a foul odor. Therefore, the NH₃ concentration in the stack flue gas is measured, controlled, and monitored. 

Example of Boiler Flue Gas, NOx Removal Process (Oil and Gas Fuels)

Solution Details

As compared with conventional NH₃ analyzers that perform measurements through a sampling system, the TDLS8000 is able to measure the NH₃ concentrations in furnaces directly and thus reduce the maintenance and running costs.

Field Data

Changes in NH₃ Injection Volume and Measured Values (Installation Point A / Without NOx Removal Equipment)

The TDLS responds to NH₃ injection volume changes at high speed and thus is able to control and monitor the optimum NH₃ injection volume.

Measurement System

• TDLS(NH₃ analyzer)
  TDLS8000-☐☐-A1-☐☐-A1-☐-N/☐
• HMI unit
  YH8000-☐☐-W-N/☐
• Cable
  K9775XA～XG
• Accessories
  If necessary, please prepare ball valve for process isolation, DC power supply etc.
  And, When P and T are big fluctuation (P; ±5kPa, T; ±10℃), please consider input P, T analog signal or transmitters connection.

Utility

• Please prepare instrument air or N₂.
  2 to 20 L/min for optioc.
  5 to 30 L/min for process window

Notes

• Power supply: 24 VDC
• Purge gas: Instrumentation air or N₂, Flow rate: 5 to 50 L/min (depending on the application)
• Dust concentration (standard): 15 g/Nm³ or less