ENGINE & TURBINE TECHNOLOGY
To meet the new
emissions standard, it was clear the turbine required a retrofi t solution
TURBINE TUNING TECH
Gas turbine combustion auto-tuning solution reduces NOx emissions by 120 tonnes a year
G
overnments around the world are cracking down on nitrogen oxide (NOx) emissions, not only for transport, but gas turbines as
well, with operators having to invest in equipment to meet ever stricter standards. To ensure a 500MW combined cycle powerplant at Tongzhou in China could meet new legislation, Sulzer engineered a customised combustion automatic tuning adjustment system (CATS). T e advanced, closed loop solution has avoided the large capital expenditure (CAPEX) and long lead times of fl ue gas denitration and burner upgrades – all while securing gas turbine effi ciency through balancing key parameters in operation.
MEETING A NEW EMISSIONS STANDARD In 2021, Jiangsu Province in China announced its “Stationary Gas Turbine Air Pollutant Emission Standard”, which stipulated that by March 2023, all gas turbines in the area will have to attain a NOx emission limit 30mg/m3
(standard
powerplant in Tongzhou with a challenge. 26
www.engineerlive.com
state, dry basis, 15% O2 ). T is presented a
T e plant’s Siemens V94.2 gas turbine was found to be emitting between 35 to 45mg/m3
of NOx during normal running.
To meet the new emissions standard, it was clear the turbine required a retrofi t solution. Operators at the powerplant approached
Sulzer, a global independent service provider (ISP) for rotating equipment. From a worldwide network of specialist service centres, Sulzer provides repairs and upgrades for all types of turbomachinery. With its ongoing approach to innovation, Sulzer off ers solutions to meet the modern operating demands of gas turbines. Consequently, the company was a natural choice to partner with in identifying the best approach to reduce emissions.
CHOOSING AN OPTIMAL SOLUTION T e fi rst option explored by Sulzer was fl ue gas denitration. Similar to diesel vehicles using AdBlue, a urea solution would be introduced into the gas stream to carry out selective catalytic reduction (SCR) - a well-established method for reducing NOx emissions. However, as the turbine did not
have this system fi tted, it would require a CAPEX of around US$2 million and an annual operating expenditure (OPEX) of US$685,000. A more cost-eff ective option was a burner upgrade. However, a low NOx burner cartridge replacement would still equate to a US$342,000 CAPEX and an annual US$137,000 OPEX. As well as being high-cost solutions, both options would have long lead times and associated downtime, not ideal for a power generation application. Sulzer instead proposed a more advanced solution. By balancing the parameters of combustion within the gas turbine, it was possible that the emissions standard could be met. T is would require a CATS, which could provide real-time, dynamic control of the process. Its key function would be to optimise combustion stability by identifying and reacting to operational thresholds, keeping NOx emissions under the legislative limit. Sulzer estimated that such a system could be developed, tested and implemented for around US$68,000. Key advantages included a relatively short turnaround time and
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