CASI STUDIO

Ammonia slip control in heavily dust-loaded fumes thanks to LAS 5000XD TDLS gas analyzer

Coal fired power plant | LAS 5000XD

Industry: Coal fired power plant in Suzhou, China.

Challenge: Measure with high accuracy NH3 in the range 0-10 ppm with a fast Response Time (RT).

APPLICATION

Chinese regulation on low NOx emissions has been in place for a while in the power generation sector. In consequence, Selective Catalytic Reduction (SCR) DeNOx systems are present in most of the plants.

At the moment, almost every power plant is using ammonia slip monitoring on the SCR processes to optimize the NOx abatement.

Different types of instruments have been used for this purpose, but most of them don’t match the regulation requirements in terms of measurement precision and robustness.

For this reason, both Chinese government and customers want to find a better solution to fulfill process control requirements. ENVEA hence put in a lot of efforts to provide customer value with its new LAS 5000XD TDLS gas analyzer.

Due to the global pandemic and travel restrictions in China, no visits or face-to-face meetings could be organized. Therefore, the collaboration between the ENVEA teams took place only remotely and thus online.

Similarly, customer training and commissioning of the analyzer was carried out remotely, demonstrating the ease of installation and operation of the LAS 5000XD gas analyzer.

SOLUTION provided

The TDLS LAS 5000XD gas analyzer was installed in a Suzhou’s coal power plant, facing harsh conditions. Indeed, the plant features a 4.5 m diameter duct where the customer needs to monitor NH₃ concentration in a heavily dust-loaded flue-gas (30-40 g/m³) at a temperature of 300°C.
Flue gas environmental protection facilities include denitrification, dust scrubber, and desulfurization. Urea hydrolysis is used as a denitrification reducing agent (DeNOx).

Each boiler is equipped with 2 SCR reactors. The outside ambient temperature is about 60°C at the installation point (see picture).
In order to adapt to these specific conditions, a tube with a 1 m pierced window was installed across the duct so that the measurement of the LAS 5000XD optical path, reduced to 1 m, is precise and optimized.

The NH₃ injection was manually adjusted, and the analyzer measurement trend followed perfectly each adjustment with a reading varying from 5-8 ppm and a Response Time around 1 s.

These results show that the in-situ LAS 5000XD TDLS gas analyzer is ready for this application and totally fit for such harsh conditions, without compromising the measurement accuracy.