Nozzle Steam Overview
In May of 1992 IPT and Allison entered into a Development Agreement to test the effects of nozzle steam on the case steam injected 501-KH engine. At that time Allison chose IPT’s Menlo Park 501-KH facility as the host site. Under the Agreement, IPT was responsible for the engine operation and Allison was responsible for the collection of the emissions data. The primary purpose of the tests was to demonstrate NOx control using a combination of nozzle steam and case steam injection. The test program was divided into four parts: dry testing, nozzle steam only testing, nozzle and case steam testing, and case steam testing with steam valve variations.
IPT’s nozzle steam development efforts for the 501 line of gas turbines started with these joint Allison/IPT tests and have continued to evolve and improve over time.
The IPT nozzle steam technology is a nozzle steam system that is similar in overall principal to the Allison 501 OEM stock nozzle steam injection system that has been in existence since the mid-1990’s. The Allison stock OEM nozzle steam system mixes saturated steam with cold fuel at the inlet to the nozzle prior to entering the combustion liner, the addition of steam in the nozzle quenches the peak flame temperature thus resulting in lower NOx emissions. Problems with the OEM design include both low mixing efficiency due to the short nozzle body mixing length, and steam condensation in the nozzle due to the injection of cold fuel into the steam. Both of these nozzle design deficiencies contribute to the inability of the stock system to achieve ultra-low NOx, stable CO, and levelized BOT temperature patterns.
Nozzle steam injection is not new for the Allison 501, and millions of hours of nozzle steam injection experience have been accumulated in the Allison 501 marketplace. The nozzle steam injection system was introduced by Allison in the 1990’s to provide an engineered solutions alternative to the Allison 501 users employing water injection systems on their gas turbines. As compared to engines employing water injection, the stock nozzle steam system proved to decrease turbine fuel consumption and increase combustion liner lifetimes.
IPT Nozzle Steam takes advantage of this experience and adds to it the capability to achieve even lower NOx emissions, controlled CO, and improved BOT flame pattern. The IPT technology improves on the stock OEM nozzle design and eliminates the problems of the stock system identified above by mixing the steam and fuel further upstream of the engine, which then results in a much higher level of mixing efficiency, called homogeneity, and by increasing the temperature of the steam and fuel mixture prior to injection into the engine. Additionally, a specialized IPT fuel nozzle is also installed in place of the stock nozzle in systems requiring very low NOx. The combined effect of these improvements to the stock system results in being able to achieve ultra-low NOx and controlled CO at very high steam injection rates, and greatly improved combustion liner lifetimes when comparing nozzle steam to water injection.
The highlights of IPT’s technology include:
- Guaranteed NOx down to as low as 5 ppm (corrected to 15% O2) for the KB5(x) engine burning pipeline natural gas. (NOx reductions to 15 ppm and lower are achieved through application of the patented CLN® technology, provided by IPT under a licensing arrangement with the patent holder.)
- Meeting all US AQMD retrofit requirements.
- Improved BOT flame pattern resulting in increased combustion liner lifetimes.
- Guaranteed nozzle steam injection quality and purity according to the Allison Installation and Design Manual (IDM) nozzle steam injection specifications.
- Reduction of CO2 greenhouse gas resulting from greatly improved turbine neat rates while operating with nozzle steam injection as opposed to operating with water injection.
Steam injection quality (moisture content) and purity (TDS content) are guaranteed by IPT to meet the Allison IDM injection steam specifications when IPT performs the steam injection piping engineering and installation. IPT Nozzle Steam can be employed on gas turbine systems with and without heat recovery and for all types of boiler HRSG designs including natural and forced circulation boilers and OTSG (Once Through Steam Generator) type boilers. Both steam quality and purity are functions of feedwater supply quality, boiler outlet steam quality, and the required injection steam moisture removal efficiency, all of which are taken into consideration during the design phase of the project and which result in a steam injection system that will remove the moisture and TDS in the injection steam down to the level required by the manufacturer of the engine.
IPT will. free of charge, perform an initial site survey to assess the applicability of the IPT Nozzle Steam System to the customer’s plant, and to determine the amount of steam piping and other modifications required to complete the installation. IPT will then present its findings along with an economic analysis and a pricing proposal for a complete turnkey installation of an IPT Nozzle Steam System at the customer’s facility.
Interested plant owners are welcome to schedule a tour to view our nozzle steam installation in Menlo Park, California. If you have questions regarding the IPT Nozzle Steam technology, or would like to schedule a plant tour, please contact: